diff --git a/client/public/locales/en/common.json b/client/public/locales/en/common.json
index 1386cb4..21c1326 100644
--- a/client/public/locales/en/common.json
+++ b/client/public/locales/en/common.json
@@ -264,7 +264,7 @@
         },
         "extra_fields": {
             "tab": "Extra Fields",
-            "description": "<p>Here you can add extra custom fields to your entities.</p><p>Once a field is added, you can not change its key or type, and for choice type fields you can not remove choices or change the multi choice state. If you remove a field, the associated data for all entities will be deleted.</p><p>Default value is only applied to new items.</p><p>Extra fields can not be sorted or filtered in the table views.</p>",
+            "description": "<p>Here you can add extra custom fields to your entities.</p><p>Once a field is added, you can not change its key or type, and for choice type fields you can not remove choices or change the multi choice state. If you remove a field, the associated data for all entities will be deleted.</p><p>The key is what other programs read/write the data as, so if your custom field is supposed to integrate with a third-party program, make sure to set it correctly. Default value is only applied to new items.</p><p>Extra fields can not be sorted or filtered in the table views.</p>",
             "params": {
                 "key": "Key",
                 "name": "Name",
diff --git a/client/src/components/column.tsx b/client/src/components/column.tsx
index 53f89a7..a773e3d 100644
--- a/client/src/components/column.tsx
+++ b/client/src/components/column.tsx
@@ -3,7 +3,7 @@ import { ColumnFilterItem, ColumnType } from "antd/es/table/interface";
 import { getFiltersForField, typeFilters } from "../utils/filtering";
 import { TableState } from "../utils/saveload";
 import { getSortOrderForField, typeSorters } from "../utils/sorting";
-import { NumberFieldUnit } from "./numberField";
+import { NumberFieldUnit, NumberFieldUnitRange } from "./numberField";
 import dayjs from "dayjs";
 import utc from "dayjs/plugin/utc";
 import { DateField, TextField } from "@refinedev/antd";
@@ -12,7 +12,8 @@ import SpoolIcon from "../icon_spool.svg?react";
 import { useTranslate } from "@refinedev/core";
 import { enrichText } from "../utils/parsing";
 import { UseQueryResult } from "@tanstack/react-query";
-import { Link, useNavigate } from "react-router-dom";
+import { Link } from "react-router-dom";
+import { Field, FieldType } from "../utils/queryFields";
 
 dayjs.extend(utc);
 
@@ -39,14 +40,19 @@ export interface Action {
 }
 
 interface BaseColumnProps<Obj extends Entity> {
-  id: keyof Obj & string;
+  id: string | string[];
   dataId?: keyof Obj & string;
   i18ncat?: string;
   i18nkey?: string;
+  title?: string;
+  sorter?: boolean;
+  t: (key: string) => string;
+  navigate: (link: string) => void;
   dataSource: Obj[];
   tableState: TableState;
   width?: number;
   actions?: (record: Obj) => Action[];
+  transform?: (value: unknown) => unknown;
 }
 
 interface FilteredColumnProps {
@@ -70,24 +76,32 @@ interface CustomColumnProps<Obj> {
 function Column<Obj extends Entity>(
   props: BaseColumnProps<Obj> & FilteredColumnProps & CustomColumnProps<Obj>
 ): ColumnType<Obj> | undefined {
-  const t = useTranslate();
-  const navigate = useNavigate();
+  const t = props.t;
+  const navigate = props.navigate;
 
   // Hide if not in showColumns
-  if (props.tableState.showColumns && !props.tableState.showColumns.includes(props.id)) {
+  const id = Array.isArray(props.id) ? props.id.join(".") : props.id;
+  if (props.tableState.showColumns && !props.tableState.showColumns.includes(id)) {
     return undefined;
   }
 
   const columnProps: ColumnType<Obj> = {
     dataIndex: props.id,
-    title: t(props.i18nkey ?? `${props.i18ncat}.fields.${props.id}`),
-    sorter: true,
-    sortOrder: getSortOrderForField(typeSorters<Obj>(props.tableState.sorters), props.dataId ?? props.id),
+    title: props.title ?? t(props.i18nkey ?? `${props.i18ncat}.fields.${props.id}`),
     filterMultiple: props.allowMultipleFilters ?? true,
     width: props.width ?? undefined,
     onCell: props.onCell ?? undefined,
   };
 
+  // Sorting
+  if (props.sorter) {
+    columnProps.sorter = true;
+    columnProps.sortOrder = getSortOrderForField(
+      typeSorters<Obj>(props.tableState.sorters),
+      props.dataId ?? (props.id as keyof Obj)
+    );
+  }
+
   // Filter
   if (props.filters && props.filteredValue) {
     columnProps.filters = props.filters;
@@ -106,7 +120,12 @@ function Column<Obj extends Entity>(
   }
 
   // Render
-  const render = props.render ?? ((value) => <>{value}</>);
+  const render =
+    props.render ??
+    ((rawValue) => {
+      const value = props.transform ? props.transform(rawValue) : rawValue;
+      return <>{value}</>;
+    });
   columnProps.render = (value, record, index) => {
     if (!props.actions) {
       return render(value, record, index);
@@ -144,13 +163,19 @@ function Column<Obj extends Entity>(
 }
 
 export function SortedColumn<Obj extends Entity>(props: BaseColumnProps<Obj>) {
-  return Column(props);
-}
-
-export function RichColumn<Obj extends Entity>(props: BaseColumnProps<Obj>) {
   return Column({
     ...props,
-    render: (value: string | undefined) => {
+    sorter: true,
+  });
+}
+
+export function RichColumn<Obj extends Entity>(
+  props: Omit<BaseColumnProps<Obj>, "transform"> & { transform?: (value: unknown) => string }
+) {
+  return Column({
+    ...props,
+    render: (rawValue: string | undefined) => {
+      const value = props.transform ? props.transform(rawValue) : rawValue;
       return enrichText(value);
     },
   });
@@ -182,7 +207,7 @@ export function FilteredQueryColumn<Obj extends Entity>(props: FilteredQueryColu
   });
 
   const typedFilters = typeFilters<Obj>(props.tableState.filters);
-  const filteredValue = getFiltersForField(typedFilters, props.dataId ?? props.id);
+  const filteredValue = getFiltersForField(typedFilters, props.dataId ?? (props.id as keyof Obj));
 
   const onFilterDropdownOpen = () => {
     query.refetch();
@@ -193,14 +218,16 @@ export function FilteredQueryColumn<Obj extends Entity>(props: FilteredQueryColu
 
 interface NumberColumnProps<Obj extends Entity> extends BaseColumnProps<Obj> {
   unit: string;
-  decimals?: number;
+  maxDecimals?: number;
+  minDecimals?: number;
   defaultText?: string;
 }
 
 export function NumberColumn<Obj extends Entity>(props: NumberColumnProps<Obj>) {
   return Column({
     ...props,
-    render: (value) => {
+    render: (rawValue) => {
+      const value = props.transform ? props.transform(rawValue) : rawValue;
       if (value === null || value === undefined) {
         return <TextField value={props.defaultText ?? ""} />;
       }
@@ -209,8 +236,8 @@ export function NumberColumn<Obj extends Entity>(props: NumberColumnProps<Obj>)
           value={value}
           unit={props.unit}
           options={{
-            maximumFractionDigits: props.decimals ?? 0,
-            minimumFractionDigits: props.decimals ?? 0,
+            maximumFractionDigits: props.maxDecimals ?? 0,
+            minimumFractionDigits: props.minDecimals ?? props.maxDecimals ?? 0,
           }}
         />
       );
@@ -221,7 +248,8 @@ export function NumberColumn<Obj extends Entity>(props: NumberColumnProps<Obj>)
 export function DateColumn<Obj extends Entity>(props: BaseColumnProps<Obj>) {
   return Column({
     ...props,
-    render: (value) => {
+    render: (rawValue) => {
+      const value = props.transform ? props.transform(rawValue) : rawValue;
       return (
         <DateField
           hidden={!value}
@@ -291,7 +319,7 @@ export function SpoolIconColumn<Obj extends Entity>(props: SpoolIconColumnProps<
   });
 
   const typedFilters = typeFilters<Obj>(props.tableState.filters);
-  const filteredValue = getFiltersForField(typedFilters, props.dataId ?? props.id);
+  const filteredValue = getFiltersForField(typedFilters, props.dataId ?? (props.id as keyof Obj));
 
   const onFilterDropdownOpen = () => {
     query.refetch();
@@ -312,7 +340,8 @@ export function SpoolIconColumn<Obj extends Entity>(props: SpoolIconColumnProps<
         },
       };
     },
-    render: (value, record: Obj) => {
+    render: (rawValue, record: Obj) => {
+      const value = props.transform ? props.transform(rawValue) : rawValue;
       const colorStr = props.color(record);
       return (
         <Row wrap={false} justify="space-around" align="middle">
@@ -334,3 +363,121 @@ export function SpoolIconColumn<Obj extends Entity>(props: SpoolIconColumnProps<
     },
   });
 }
+
+export function NumberRangeColumn<Obj extends Entity>(props: NumberColumnProps<Obj>) {
+  return Column({
+    ...props,
+    render: (rawValue) => {
+      const value = props.transform ? props.transform(rawValue) : rawValue;
+      if (value === null || value === undefined) {
+        return <TextField value={props.defaultText ?? ""} />;
+      }
+      if (!Array.isArray(value) || value.length !== 2) {
+        return <TextField value={props.defaultText ?? ""} />;
+      }
+
+      return (
+        <NumberFieldUnitRange
+          value={value}
+          unit={props.unit}
+          options={{
+            maximumFractionDigits: props.maxDecimals ?? 0,
+            minimumFractionDigits: props.minDecimals ?? props.maxDecimals ?? 0,
+          }}
+        />
+      );
+    },
+  });
+}
+
+export function CustomFieldColumn<Obj extends Entity>(props: Omit<BaseColumnProps<Obj>, "id"> & { field: Field }) {
+  const field = props.field;
+  const commonProps = {
+    ...props,
+    id: ["extra", field.key],
+    title: field.name,
+    sorter: false,
+    transform: (value: unknown) => {
+      if (value === null || value === undefined) {
+        return undefined;
+      }
+      return JSON.parse(value as string);
+    },
+  };
+
+  if (field.field_type === FieldType.integer) {
+    return NumberColumn({
+      ...commonProps,
+      unit: field.unit ?? "",
+      maxDecimals: 0,
+    });
+  } else if (field.field_type === FieldType.float) {
+    return NumberColumn({
+      ...commonProps,
+      unit: field.unit ?? "",
+      minDecimals: 0,
+      maxDecimals: 3,
+    });
+  } else if (field.field_type === FieldType.integer_range) {
+    return NumberRangeColumn({
+      ...commonProps,
+      unit: field.unit ?? "",
+      maxDecimals: 0,
+    });
+  } else if (field.field_type === FieldType.float_range) {
+    return NumberRangeColumn({
+      ...commonProps,
+      unit: field.unit ?? "",
+      minDecimals: 0,
+      maxDecimals: 3,
+    });
+  } else if (field.field_type === FieldType.text) {
+    return RichColumn({
+      ...commonProps,
+    });
+  } else if (field.field_type === FieldType.datetime) {
+    return DateColumn({
+      ...commonProps,
+    });
+  } else if (field.field_type === FieldType.boolean) {
+    return Column({
+      ...commonProps,
+      render: (rawValue) => {
+        const value = commonProps.transform ? commonProps.transform(rawValue) : rawValue;
+        let text;
+        if (value === undefined || value === null) {
+          text = "";
+        } else if (value) {
+          text = props.t("yes");
+        } else {
+          text = props.t("no");
+        }
+        return <TextField value={text} />;
+      },
+    });
+  } else if (field.field_type === FieldType.choice && !field.multi_choice) {
+    return Column({
+      ...commonProps,
+      render: (rawValue) => {
+        const value = commonProps.transform ? commonProps.transform(rawValue) : rawValue;
+        return <TextField value={value} />;
+      },
+    });
+  } else if (field.field_type === FieldType.choice && field.multi_choice) {
+    return Column({
+      ...commonProps,
+      render: (rawValue) => {
+        const value = commonProps.transform ? commonProps.transform(rawValue) : rawValue;
+        return <TextField value={(value as string[] | undefined)?.join(", ")} />;
+      },
+    });
+  } else {
+    return Column({
+      ...commonProps,
+      render: (rawValue) => {
+        const value = commonProps.transform ? commonProps.transform(rawValue) : rawValue;
+        return <TextField value={value} />;
+      },
+    });
+  }
+}
diff --git a/client/src/components/dateTimePicker.tsx b/client/src/components/dateTimePicker.tsx
new file mode 100644
index 0000000..4097682
--- /dev/null
+++ b/client/src/components/dateTimePicker.tsx
@@ -0,0 +1,33 @@
+import { DatePicker } from "antd";
+import dayjs from "dayjs";
+import utc from "dayjs/plugin/utc";
+import timezone from "dayjs/plugin/timezone";
+import advancedFormat from "dayjs/plugin/advancedFormat";
+
+dayjs.extend(utc);
+dayjs.extend(timezone);
+dayjs.extend(advancedFormat);
+
+// Localized date time format with timezone
+const dateTimeFormat = "YYYY-MM-DD HH:mm:ss";
+
+export function DateTimePicker<T extends string | dayjs.Dayjs>(props: { value?: T; onChange?: (value?: T) => void }) {
+  return (
+    <DatePicker
+      showTime={{ use12Hours: false }}
+      format={dateTimeFormat}
+      value={props.value ? dayjs(props.value) : undefined}
+      onChange={(value) => {
+        if (value) {
+          if (typeof props.value === "string") {
+            props.onChange?.(value.toISOString() as T);
+          } else {
+            props.onChange?.(value as T);
+          }
+        } else {
+          props.onChange?.(undefined);
+        }
+      }}
+    />
+  );
+}
diff --git a/client/src/components/extraFields.tsx b/client/src/components/extraFields.tsx
new file mode 100644
index 0000000..ab2bacc
--- /dev/null
+++ b/client/src/components/extraFields.tsx
@@ -0,0 +1,211 @@
+import { DateField, TextField } from "@refinedev/antd";
+import { Field, FieldType } from "../utils/queryFields";
+import { NumberFieldUnit, NumberFieldUnitRange } from "./numberField";
+import { enrichText } from "../utils/parsing";
+import dayjs from "dayjs";
+import utc from "dayjs/plugin/utc";
+import { Checkbox, Form, Input, InputNumber, Select, Typography } from "antd";
+import { FormItemProps, Rule } from "antd/es/form";
+import { DateTimePicker } from "./dateTimePicker";
+import { InputNumberRange } from "./inputNumberRange";
+
+dayjs.extend(utc);
+
+const { Title } = Typography;
+
+/**
+ * Title and value to display an extra field. Used for the show pages.
+ * @param props
+ * @returns
+ */
+export function ExtraFieldDisplay(props: { field: Field; value: string | undefined }) {
+  const { field, value } = props;
+
+  let item;
+  if (value !== undefined) {
+    const parsedValue = JSON.parse(value);
+
+    if (field.field_type === FieldType.integer) {
+      item = (
+        <NumberFieldUnit
+          value={parsedValue ?? ""}
+          unit={field.unit ?? ""}
+          options={{
+            maximumFractionDigits: 0,
+            minimumFractionDigits: 0,
+          }}
+        />
+      );
+    } else if (field.field_type === FieldType.float) {
+      item = (
+        <NumberFieldUnit
+          value={parsedValue ?? ""}
+          unit={field.unit ?? ""}
+          options={{
+            maximumFractionDigits: 3,
+            minimumFractionDigits: 0,
+          }}
+        />
+      );
+    } else if (field.field_type === FieldType.integer_range || field.field_type === FieldType.float_range) {
+      if (!Array.isArray(parsedValue) || parsedValue.length !== 2) {
+        return <TextField value={parsedValue} />;
+      }
+      item = (
+        <NumberFieldUnitRange
+          value={parsedValue}
+          unit={field.unit ?? ""}
+          options={{
+            maximumFractionDigits: field.field_type === FieldType.float_range ? 3 : 0,
+            minimumFractionDigits: 0,
+          }}
+        />
+      );
+    } else if (field.field_type === FieldType.text) {
+      item = <TextField value={enrichText(parsedValue)} />;
+    } else if (field.field_type === FieldType.datetime) {
+      item = (
+        <DateField
+          value={dayjs.utc(parsedValue).local()}
+          title={dayjs.utc(parsedValue).local().format()}
+          format="YYYY-MM-DD HH:mm:ss"
+        />
+      );
+    } else if (field.field_type === FieldType.boolean) {
+      item = <TextField value={parsedValue ? "Yes" : "No"} />;
+    } else if (field.field_type === FieldType.choice && !field.multi_choice) {
+      item = <TextField value={parsedValue} />;
+    } else if (field.field_type === FieldType.choice && field.multi_choice) {
+      item = <TextField value={parsedValue.join(", ")} />;
+    } else {
+      throw new Error(`Unknown field type: ${field.field_type}`);
+    }
+  } else {
+    item = <></>;
+  }
+
+  return (
+    <>
+      <Title level={5}>{field.name}</Title>
+      {item}
+    </>
+  );
+}
+
+/**
+ * Form item for an extra field. Used for the edit pages.
+ * @param props
+ * @returns
+ */
+export function ExtraFieldFormItem(props: { field: Field; setDefaultValue?: boolean }) {
+  const { field } = props;
+
+  let inputNode;
+  const rules: Rule[] = [
+    {
+      required: false,
+    },
+  ];
+  const formItemProps: FormItemProps = {};
+  if (field.field_type === FieldType.integer) {
+    inputNode = <InputNumber addonAfter={field.unit} precision={0} />;
+    rules.push({
+      type: "integer",
+    });
+  } else if (field.field_type === FieldType.float) {
+    inputNode = <InputNumber addonAfter={field.unit} precision={3} />;
+    rules.push({
+      type: "number",
+    });
+  } else if (field.field_type === FieldType.integer_range) {
+    inputNode = <InputNumberRange unit={field.unit} precision={0} />;
+  } else if (field.field_type === FieldType.float_range) {
+    inputNode = <InputNumberRange unit={field.unit} precision={3} />;
+  } else if (field.field_type === FieldType.text) {
+    inputNode = <Input />;
+    rules.push({
+      type: "string",
+    });
+  } else if (field.field_type === FieldType.datetime) {
+    inputNode = <DateTimePicker />;
+  } else if (field.field_type === FieldType.boolean) {
+    inputNode = <Checkbox />;
+    formItemProps.valuePropName = "checked";
+    rules.push({
+      type: "boolean",
+    });
+  } else if (field.field_type === FieldType.choice) {
+    inputNode = (
+      <Select
+        mode={field.multi_choice ? "multiple" : undefined}
+        options={field.choices?.map((choice) => ({ label: choice, value: choice }))}
+      />
+    );
+    rules.push({
+      type: field.multi_choice ? "array" : "string",
+    });
+  } else {
+    throw new Error(`Unknown field type: ${field.field_type}`);
+  }
+
+  if (props.setDefaultValue) {
+    formItemProps.initialValue = field.default_value;
+  }
+
+  return (
+    <Form.Item label={field.name} name={["extra", field.key]} rules={rules} {...formItemProps}>
+      {inputNode}
+    </Form.Item>
+  );
+}
+
+/**
+ * Convert the string-based value extra key-values of an entity to their JSON-parsed values.
+ * @param obj
+ * @returns
+ */
+export function ParsedExtras<T extends { extra?: { [key: string]: string } }>(
+  obj: T
+): Omit<T, "extra"> & { extra?: { [key: string]: unknown } } {
+  if (obj.extra) {
+    const newExtra: { [key: string]: unknown } = {};
+    Object.entries(obj.extra).forEach(([key, value]) => {
+      try {
+        newExtra[key] = JSON.parse(value);
+      } catch (e) {
+        newExtra[key] = value;
+      }
+    });
+    return {
+      ...obj,
+      extra: newExtra,
+    };
+  } else {
+    return obj;
+  }
+}
+
+/**
+ * Convert the JSON-parsed value extra key-values of an entity to their string values.
+ * @param obj
+ * @returns
+ */
+export function StringifiedExtras<T extends { extra?: { [key: string]: unknown } }>(
+  obj: T
+): Omit<T, "extra"> & { extra?: { [key: string]: string } } {
+  if (obj.extra) {
+    const newExtra: { [key: string]: string } = {};
+    Object.entries(obj.extra).forEach(([key, value]) => {
+      newExtra[key] = JSON.stringify(value);
+    });
+    return {
+      ...obj,
+      extra: newExtra,
+    };
+  } else {
+    return {
+      ...obj,
+      extra: undefined,
+    };
+  }
+}
diff --git a/client/src/components/inputNumberRange.tsx b/client/src/components/inputNumberRange.tsx
new file mode 100644
index 0000000..23da031
--- /dev/null
+++ b/client/src/components/inputNumberRange.tsx
@@ -0,0 +1,57 @@
+import { InputNumber } from "antd";
+
+function parseValue(value?: (number | null)[]): [number | null, number | null] {
+  if (value === undefined) {
+    return [null, null];
+  }
+
+  if (!Array.isArray(value) || value.length !== 2) {
+    return [null, null];
+  }
+
+  const [min, max] = value;
+
+  return [min, max];
+}
+
+/**
+ * An Ant Design compatible form input for a number range.
+ * @param props
+ * @returns
+ */
+export function InputNumberRange(props: {
+  /** Decimal precision */ precision?: number;
+  /** Unit to display */ unit?: string;
+  /** Value state */ value?: (number | null)[] | undefined;
+  /** Called when input changes. Used to update value state. */ onChange?: (value: (number | null)[]) => void;
+}) {
+  const [min, max] = parseValue(props.value);
+
+  return (
+    <>
+      <InputNumber
+        value={min}
+        precision={props.precision ?? 0}
+        addonAfter={props.unit}
+        style={{ maxWidth: 110 }}
+        onChange={(value) => {
+          if (props.onChange) {
+            props.onChange([value, max]);
+          }
+        }}
+      />
+      {" \u2013 "}
+      <InputNumber
+        value={max}
+        precision={props.precision ?? 0}
+        addonAfter={props.unit}
+        style={{ maxWidth: 110 }}
+        onChange={(value) => {
+          if (props.onChange) {
+            props.onChange([min, value]);
+          }
+        }}
+      />
+    </>
+  );
+}
diff --git a/client/src/components/numberField.tsx b/client/src/components/numberField.tsx
index b8bf0da..facb258 100644
--- a/client/src/components/numberField.tsx
+++ b/client/src/components/numberField.tsx
@@ -26,3 +26,36 @@ export const NumberFieldUnit: React.FC<Props> = ({ value, locale, options, ...re
     </Text>
   );
 };
+
+/**
+ * Like a {@link NumberFieldUnit} but for a range of numbers.
+ * @param props
+ * @returns
+ */
+export function NumberFieldUnitRange(props: {
+  value: (number | null)[] | undefined;
+  unit?: string;
+  options?: Intl.NumberFormatOptions;
+}) {
+  const { value, unit, options } = props;
+
+  if (value === undefined) {
+    console.warn("NumberFieldUnitRange received undefined value");
+    return <></>;
+  }
+
+  if (!Array.isArray(value) || value.length !== 2) {
+    console.warn("NumberFieldUnitRange received invalid value", value);
+    return <></>;
+  }
+
+  const [min, max] = value;
+
+  return (
+    <>
+      {min === null ? <></> : <NumberFieldUnit value={min} unit={unit ?? ""} options={options} />}
+      {" \u2013 "}
+      {max === null ? <></> : <NumberFieldUnit value={max} unit={unit ?? ""} options={options} />}
+    </>
+  );
+}
diff --git a/client/src/pages/filaments/create.tsx b/client/src/pages/filaments/create.tsx
index 4ce1813..58e8a46 100644
--- a/client/src/pages/filaments/create.tsx
+++ b/client/src/pages/filaments/create.tsx
@@ -1,11 +1,20 @@
 import React from "react";
-import { IResourceComponentsProps, useTranslate } from "@refinedev/core";
+import { HttpError, IResourceComponentsProps, useTranslate } from "@refinedev/core";
 import { Create, useForm, useSelect } from "@refinedev/antd";
 import { Form, Input, Select, InputNumber, ColorPicker, Button } from "antd";
 import TextArea from "antd/es/input/TextArea";
 import { numberFormatter, numberParser } from "../../utils/parsing";
 import { IVendor } from "../vendors/model";
 import { IFilament } from "./model";
+import { EntityType, FieldType, useGetFields } from "../../utils/queryFields";
+import { ExtraFieldFormItem, StringifiedExtras } from "../../components/extraFields";
+import dayjs from "dayjs";
+import utc from "dayjs/plugin/utc";
+
+dayjs.extend(utc);
+
+// IFilamentParsedExtras is the same as IFilament, but with the extra field parsed into its real types
+type IFilamentParsedExtras = Omit<IFilament, "extra"> & { extra?: { [key: string]: unknown } };
 
 interface CreateOrCloneProps {
   mode: "create" | "clone";
@@ -13,10 +22,20 @@ interface CreateOrCloneProps {
 
 export const FilamentCreate: React.FC<IResourceComponentsProps & CreateOrCloneProps> = (props) => {
   const t = useTranslate();
+  const extraFields = useGetFields(EntityType.filament);
 
-  const { form, formProps, formLoading, onFinish, redirect } = useForm<IFilament>();
+  const { form, formProps, formLoading, onFinish, redirect } = useForm<
+    IFilament,
+    HttpError,
+    IFilamentParsedExtras,
+    IFilamentParsedExtras
+  >();
 
-  if (props.mode === "clone" && formProps.initialValues) {
+  if (!formProps.initialValues) {
+    formProps.initialValues = {};
+  }
+
+  if (props.mode === "clone") {
     // Fix the vendor_id
     if (formProps.initialValues.vendor) {
       formProps.initialValues.vendor_id = formProps.initialValues.vendor.id;
@@ -24,7 +43,7 @@ export const FilamentCreate: React.FC<IResourceComponentsProps & CreateOrClonePr
   }
 
   const handleSubmit = async (redirectTo: "list" | "edit" | "create") => {
-    const values = await form.validateFields();
+    const values = StringifiedExtras(await form.validateFields());
     await onFinish(values);
     redirect(redirectTo, (values as IFilament).id);
   };
@@ -34,6 +53,21 @@ export const FilamentCreate: React.FC<IResourceComponentsProps & CreateOrClonePr
     optionLabel: "name",
   });
 
+  // Use useEffect to update the form's initialValues when the extra fields are loaded
+  // This is necessary because the form is rendered before the extra fields are loaded
+  React.useEffect(() => {
+    extraFields.data?.forEach((field) => {
+      if (formProps.initialValues && field.default_value) {
+        let parsedValue = JSON.parse(field.default_value as string);
+        if (field.field_type === FieldType.datetime) {
+          parsedValue = dayjs(parsedValue);
+        }
+
+        form.setFieldsValue({ extra: { [field.key]: parsedValue } });
+      }
+    });
+  }, [form, extraFields.data, formProps.initialValues]);
+
   return (
     <Create
       title={props.mode === "create" ? t("filament.titles.create") : t("filament.titles.clone")}
@@ -229,6 +263,9 @@ export const FilamentCreate: React.FC<IResourceComponentsProps & CreateOrClonePr
         >
           <TextArea maxLength={1024} />
         </Form.Item>
+        {extraFields.data?.map((field, index) => (
+          <ExtraFieldFormItem key={index} field={field} />
+        ))}
       </Form>
     </Create>
   );
diff --git a/client/src/pages/filaments/edit.tsx b/client/src/pages/filaments/edit.tsx
index 8b44a6f..ba77591 100644
--- a/client/src/pages/filaments/edit.tsx
+++ b/client/src/pages/filaments/edit.tsx
@@ -1,5 +1,5 @@
 import React, { useState } from "react";
-import { IResourceComponentsProps, useTranslate } from "@refinedev/core";
+import { HttpError, IResourceComponentsProps, useTranslate } from "@refinedev/core";
 import { Edit, useForm, useSelect } from "@refinedev/antd";
 import { Form, Input, DatePicker, Select, InputNumber, ColorPicker, message, Alert } from "antd";
 import dayjs from "dayjs";
@@ -7,30 +7,62 @@ import TextArea from "antd/es/input/TextArea";
 import { numberFormatter, numberParser } from "../../utils/parsing";
 import { IVendor } from "../vendors/model";
 import { IFilament } from "./model";
+import { EntityType, useGetFields } from "../../utils/queryFields";
+import { ExtraFieldFormItem, StringifiedExtras } from "../../components/extraFields";
+import { ParsedExtras } from "../../components/extraFields";
+
+// IFilamentParsedExtras is the same as IFilament, but with the extra field parsed into its real types
+type IFilamentParsedExtras = Omit<IFilament, "extra"> & { extra?: { [key: string]: unknown } };
+
+/*
+The API returns the extra fields as JSON values, but we need to parse them into their real types
+in order for Ant design's form to work properly. ParsedExtras does this for us.
+We also need to stringify them again before sending them back to the API, which is done by overriding
+the form's onFinish method. Form.Item's normalize should do this, but it doesn't seem to work.
+*/
 
 export const FilamentEdit: React.FC<IResourceComponentsProps> = () => {
   const t = useTranslate();
   const [messageApi, contextHolder] = message.useMessage();
   const [hasChanged, setHasChanged] = useState(false);
+  const extraFields = useGetFields(EntityType.filament);
 
-  const { formProps, saveButtonProps } = useForm<IFilament>({
+  const { formProps, saveButtonProps } = useForm<IFilament, HttpError, IFilamentParsedExtras, IFilamentParsedExtras>({
     liveMode: "manual",
     onLiveEvent() {
       // Warn the user if the filament has been updated since the form was opened
       messageApi.warning(t("filament.form.filament_updated"));
       setHasChanged(true);
     },
+    queryOptions: {
+      select(data) {
+        return {
+          data: ParsedExtras(data.data),
+        };
+      },
+    },
   });
 
+  // Get vendor selection options
   const { selectProps } = useSelect<IVendor>({
     resource: "vendor",
     optionLabel: "name",
   });
 
+  // Add the vendor_id field to the form
   if (formProps.initialValues) {
     formProps.initialValues["vendor_id"] = formProps.initialValues["vendor"]?.id;
   }
 
+  // Override the form's onFinish method to stringify the extra fields
+  const originalOnFinish = formProps.onFinish;
+  formProps.onFinish = (allValues: IFilamentParsedExtras) => {
+    if (allValues !== undefined && allValues !== null) {
+      allValues = StringifiedExtras(allValues);
+    }
+    originalOnFinish?.(allValues);
+  };
+
   return (
     <Edit saveButtonProps={saveButtonProps}>
       {contextHolder}
@@ -246,6 +278,9 @@ export const FilamentEdit: React.FC<IResourceComponentsProps> = () => {
         >
           <TextArea maxLength={1024} />
         </Form.Item>
+        {extraFields.data?.map((field, index) => (
+          <ExtraFieldFormItem key={index} field={field} />
+        ))}
       </Form>
       {hasChanged && <Alert description={t("filament.form.filament_updated")} type="warning" showIcon />}
     </Edit>
diff --git a/client/src/pages/filaments/list.tsx b/client/src/pages/filaments/list.tsx
index 09b1356..c4a27c7 100644
--- a/client/src/pages/filaments/list.tsx
+++ b/client/src/pages/filaments/list.tsx
@@ -15,6 +15,7 @@ import {
   SortedColumn,
   SpoolIconColumn,
   ActionsColumn,
+  CustomFieldColumn,
 } from "../../components/column";
 import {
   useSpoolmanArticleNumbers,
@@ -24,9 +25,13 @@ import {
 } from "../../components/otherModels";
 import { useLiveify } from "../../components/liveify";
 import { removeUndefined } from "../../utils/filtering";
+import { EntityType, useGetFields } from "../../utils/queryFields";
+import { useNavigate } from "react-router-dom";
 
 dayjs.extend(utc);
 
+// Extra is a key-value dict
+
 interface IFilamentCollapsed extends Omit<IFilament, "vendor"> {
   "vendor.name": string | null;
 }
@@ -71,6 +76,10 @@ const defaultColumns = allColumns.filter(
 export const FilamentList: React.FC<IResourceComponentsProps> = () => {
   const t = useTranslate();
   const invalidate = useInvalidate();
+  const navigate = useNavigate();
+  const extraFields = useGetFields(EntityType.filament);
+
+  const allColumnsWithExtraFields = [...allColumns, ...(extraFields.data?.map((field) => "extra." + field.key) ?? [])];
 
   // Load initial state
   const initialState = useInitialTableState(namespace);
@@ -145,6 +154,15 @@ export const FilamentList: React.FC<IResourceComponentsProps> = () => {
     { name: t("buttons.clone"), icon: <PlusSquareOutlined />, link: cloneUrl("filament", record.id) },
   ];
 
+  const commonProps = {
+    t,
+    navigate,
+    actions,
+    dataSource,
+    tableState,
+    sorter: true,
+  };
+
   return (
     <List
       headerButtons={({ defaultButtons }) => (
@@ -163,10 +181,20 @@ export const FilamentList: React.FC<IResourceComponentsProps> = () => {
           <Dropdown
             trigger={["click"]}
             menu={{
-              items: allColumns.map((column_id) => ({
-                key: column_id,
-                label: t(translateColumnI18nKey(column_id)),
-              })),
+              items: allColumnsWithExtraFields.map((column_id) => {
+                if (column_id.indexOf("extra.") === 0) {
+                  const extraField = extraFields.data?.find((field) => "extra." + field.key === column_id);
+                  return {
+                    key: column_id,
+                    label: extraField?.name ?? column_id,
+                  };
+                }
+
+                return {
+                  key: column_id,
+                  label: t(translateColumnI18nKey(column_id)),
+                };
+              }),
               selectedKeys: showColumns,
               selectable: true,
               multiple: true,
@@ -195,129 +223,107 @@ export const FilamentList: React.FC<IResourceComponentsProps> = () => {
         rowKey="id"
         columns={removeUndefined([
           SortedColumn({
+            ...commonProps,
             id: "id",
             i18ncat: "filament",
-            actions,
-            dataSource,
-            tableState,
             width: 70,
           }),
           FilteredQueryColumn({
+            ...commonProps,
             id: "vendor.name",
             i18nkey: "filament.fields.vendor_name",
-            actions,
-            dataSource,
-            tableState,
             filterValueQuery: useSpoolmanVendors(),
           }),
           SpoolIconColumn({
+            ...commonProps,
             id: "name",
             i18ncat: "filament",
             color: (record: IFilamentCollapsed) => record.color_hex,
-            actions,
-            dataSource,
-            tableState,
             filterValueQuery: useSpoolmanFilamentNames(),
           }),
           FilteredQueryColumn({
+            ...commonProps,
             id: "material",
             i18ncat: "filament",
-            actions,
-            dataSource,
-            tableState,
             filterValueQuery: useSpoolmanMaterials(),
             width: 110,
           }),
           SortedColumn({
+            ...commonProps,
             id: "price",
             i18ncat: "filament",
-            actions,
-            dataSource,
-            tableState,
             width: 80,
           }),
           NumberColumn({
+            ...commonProps,
             id: "density",
             i18ncat: "filament",
             unit: "g/cm³",
-            decimals: 2,
-            actions,
-            dataSource,
-            tableState,
+            maxDecimals: 2,
             width: 100,
           }),
           NumberColumn({
+            ...commonProps,
             id: "diameter",
             i18ncat: "filament",
             unit: "mm",
-            decimals: 2,
-            actions,
-            dataSource,
-            tableState,
+            maxDecimals: 2,
             width: 100,
           }),
           NumberColumn({
+            ...commonProps,
             id: "weight",
             i18ncat: "filament",
             unit: "g",
-            decimals: 1,
-            actions,
-            dataSource,
-            tableState,
+            maxDecimals: 1,
             width: 100,
           }),
           NumberColumn({
+            ...commonProps,
             id: "spool_weight",
             i18ncat: "filament",
             unit: "g",
-            decimals: 1,
-            actions,
-            dataSource,
-            tableState,
+            maxDecimals: 1,
             width: 100,
           }),
           FilteredQueryColumn({
+            ...commonProps,
             id: "article_number",
             i18ncat: "filament",
-            actions,
-            dataSource,
-            tableState,
             filterValueQuery: useSpoolmanArticleNumbers(),
             width: 130,
           }),
           NumberColumn({
+            ...commonProps,
             id: "settings_extruder_temp",
             i18ncat: "filament",
             unit: "°C",
-            decimals: 0,
-            actions,
-            dataSource,
-            tableState,
+            maxDecimals: 0,
             width: 100,
           }),
           NumberColumn({
+            ...commonProps,
             id: "settings_bed_temp",
             i18ncat: "filament",
             unit: "°C",
-            decimals: 0,
-            actions,
-            dataSource,
-            tableState,
+            maxDecimals: 0,
             width: 100,
           }),
           DateColumn({
+            ...commonProps,
             id: "registered",
             i18ncat: "filament",
-            actions,
-            dataSource,
-            tableState,
           }),
+          ...(extraFields.data?.map((field) => {
+            return CustomFieldColumn({
+              ...commonProps,
+              field,
+            });
+          }) ?? []),
           RichColumn({
+            ...commonProps,
             id: "comment",
             i18ncat: "filament",
-            actions,
-            dataSource,
-            tableState,
             width: 150,
           }),
           ActionsColumn(actions),
diff --git a/client/src/pages/filaments/model.tsx b/client/src/pages/filaments/model.tsx
index 4c3207c..3558c94 100644
--- a/client/src/pages/filaments/model.tsx
+++ b/client/src/pages/filaments/model.tsx
@@ -16,4 +16,5 @@ export interface IFilament {
   settings_extruder_temp?: number;
   settings_bed_temp?: number;
   color_hex?: string;
+  extra: { [key: string]: string };
 }
diff --git a/client/src/pages/filaments/show.tsx b/client/src/pages/filaments/show.tsx
index e7ef2fd..ecb780f 100644
--- a/client/src/pages/filaments/show.tsx
+++ b/client/src/pages/filaments/show.tsx
@@ -8,6 +8,8 @@ import utc from "dayjs/plugin/utc";
 import { IFilament } from "./model";
 import { enrichText } from "../../utils/parsing";
 import { useNavigate } from "react-router-dom";
+import { EntityType, useGetFields } from "../../utils/queryFields";
+import { ExtraFieldDisplay } from "../../components/extraFields";
 dayjs.extend(utc);
 
 const { Title } = Typography;
@@ -15,6 +17,7 @@ const { Title } = Typography;
 export const FilamentShow: React.FC<IResourceComponentsProps> = () => {
   const t = useTranslate();
   const navigate = useNavigate();
+  const extraFields = useGetFields(EntityType.filament);
   const { queryResult } = useShow<IFilament>({
     liveMode: "auto",
   });
@@ -74,8 +77,6 @@ export const FilamentShow: React.FC<IResourceComponentsProps> = () => {
       />
       <Title level={5}>{t("filament.fields.name")}</Title>
       <TextField value={record?.name} />
-      {/* <Title level={5}>{t("filament.fields.id")}</Title>
-      {vendorIsLoading ? <>Loading...</> : <>{vendorData?.data?.id}</>} */}
       <Title level={5}>{t("filament.fields.color_hex")}</Title>
       <TextField value={record?.color_hex} />
       <Title level={5}>{t("filament.fields.material")}</Title>
@@ -134,6 +135,9 @@ export const FilamentShow: React.FC<IResourceComponentsProps> = () => {
       <TextField value={record?.article_number} />
       <Title level={5}>{t("filament.fields.comment")}</Title>
       <TextField value={enrichText(record?.comment)} />
+      {extraFields?.data?.map((field, index) => (
+        <ExtraFieldDisplay key={index} field={field} value={record?.extra[field.key]} />
+      ))}
     </Show>
   );
 };
diff --git a/client/src/pages/settings/ExtraFieldsSettings.tsx b/client/src/pages/settings/ExtraFieldsSettings.tsx
index 2efe9b3..7528a8f 100644
--- a/client/src/pages/settings/ExtraFieldsSettings.tsx
+++ b/client/src/pages/settings/ExtraFieldsSettings.tsx
@@ -1,7 +1,6 @@
 import {
   Button,
   Checkbox,
-  DatePicker,
   Flex,
   Form,
   FormInstance,
@@ -13,7 +12,7 @@ import {
   Table,
   message,
 } from "antd";
-import { EntityType, Field, FieldType, useDeleteField, useGetFields, useSetField } from "./queryFields";
+import { EntityType, Field, FieldType, useDeleteField, useGetFields, useSetField } from "../../utils/queryFields";
 import { useTranslate } from "@refinedev/core";
 import { useState } from "react";
 import { ColumnType } from "antd/es/table";
@@ -25,13 +24,15 @@ import dayjs from "dayjs";
 import utc from "dayjs/plugin/utc";
 import timezone from "dayjs/plugin/timezone";
 import advancedFormat from "dayjs/plugin/advancedFormat";
+import { DateTimePicker } from "../../components/dateTimePicker";
+import { InputNumberRange } from "../../components/inputNumberRange";
 
 dayjs.extend(utc);
 dayjs.extend(timezone);
 dayjs.extend(advancedFormat);
 
 // Localized date time format with timezone
-const dateTimeFormat = "YYYY-MM-DD HH:mm:ss z";
+const dateTimeFormat = "YYYY-MM-DD HH:mm:ss";
 
 interface EditableCellProps extends React.HTMLAttributes<HTMLElement> {
   record: FieldHolder;
@@ -194,19 +195,19 @@ const EditableCell: React.FC<EditableCellProps> = ({ record, editing, dataIndex,
         type: "number",
       });
     } else if (fieldType === FieldType.integer_range) {
-      inputNode = <Input placeholder="Example: 180 - 210" />;
+      inputNode = <InputNumberRange precision={0} />;
       rules.push({
-        type: "string",
-        pattern: /^-?\d+\s*-\s*-?\d+$/,
+        type: "array",
+        len: 2,
       });
     } else if (fieldType === FieldType.float_range) {
-      inputNode = <Input placeholder="Example: 1.34 - 2.90" />;
+      inputNode = <InputNumberRange precision={3} />;
       rules.push({
-        type: "string",
-        pattern: /^-?\d+([.,]\d+)?\s*-\s*-?\d+([.,]\d+)?$/,
+        type: "array",
+        len: 2,
       });
     } else if (fieldType === FieldType.datetime) {
-      inputNode = <DatePicker format={dateTimeFormat} showTime={{ use12Hours: false }} />;
+      inputNode = <DateTimePicker />;
     } else if (fieldType === FieldType.choice) {
       inputNode = (
         <Select
@@ -300,23 +301,12 @@ export function ExtraFieldsSettings() {
 
   const edit = (record: Partial<Field> & { key: React.Key }) => {
     const values = { ...record };
-    console.log(values);
+
     if (values.default_value && typeof values.default_value === "string") {
       const def = JSON.parse(values.default_value);
-      if (Array.isArray(def)) {
-        if (values.field_type === FieldType.choice) {
-          values.default_value = def.join(", ");
-        } else if (values.field_type === FieldType.integer_range || values.field_type === FieldType.float_range) {
-          values.default_value = `${def[0]} - ${def[1]}`;
-        } else {
-          values.default_value = undefined;
-        }
-      } else if (values.field_type === FieldType.datetime) {
-        // Parse as dayjs
-        values.default_value = dayjs(def);
-      } else if (values.field_type === FieldType.boolean) {
+      if (values.field_type === FieldType.boolean) {
         values.default_value = def ? true : false;
-      } else if (values.field_type === FieldType.text) {
+      } else {
         values.default_value = def;
       }
     } else {
@@ -383,24 +373,16 @@ export function ExtraFieldsSettings() {
     // Do some value conversions
     try {
       // Convert float and integer range to array using the validation regex
-      if (updatedField.field_type === FieldType.float_range && typeof updatedField.default_value === "string") {
-        const pattern = /^(-?\d+(?:[.,]\d+)?)\s*-\s*(-?\d+(?:[.,]\d+)?)$/;
-        const matches = updatedField.default_value.match(pattern);
-        if (matches) {
-          const val1 = parseFloat(matches[1].replace(",", "."));
-          const val2 = parseFloat(matches[2].replace(",", "."));
-          updatedField.default_value = JSON.stringify([Math.min(val1, val2), Math.max(val1, val2)]);
-        }
-      } else if (
-        updatedField.field_type === FieldType.integer_range &&
-        typeof updatedField.default_value === "string"
+      if (
+        (updatedField.field_type === FieldType.float_range || updatedField.field_type === FieldType.integer_range) &&
+        updatedField.default_value !== undefined
       ) {
-        const pattern = /^(-?\d+)\s*-\s*(-?\d+)$/;
-        const matches = updatedField.default_value.match(pattern);
-        if (matches) {
-          const val1 = parseInt(matches[1]);
-          const val2 = parseInt(matches[2]);
-          updatedField.default_value = JSON.stringify([Math.min(val1, val2), Math.max(val1, val2)]);
+        if (Array.isArray(updatedField.default_value)) {
+          const val1 = updatedField.default_value[0];
+          const val2 = updatedField.default_value[1];
+          updatedField.default_value = JSON.stringify([val1, val2]);
+        } else {
+          console.warn("Invalid default_value for range", updatedField.default_value);
         }
       } else {
         // Just stringify all other values
@@ -441,8 +423,6 @@ export function ExtraFieldsSettings() {
 
     // Submit it!
     try {
-      console.log(updatedField);
-
       setIsSubmitting(true);
 
       setField.reset();
@@ -511,7 +491,7 @@ export function ExtraFieldsSettings() {
           (Array.isArray(val) && record.field.field_type === FieldType.integer_range) ||
           record.field.field_type === FieldType.float_range
         ) {
-          return `${val[0]} - ${val[1]}`;
+          return `${val[0]} \u2013 ${val[1]}`;
         } else {
           return null;
         }
diff --git a/client/src/pages/settings/GeneralSettings.tsx b/client/src/pages/settings/GeneralSettings.tsx
index 48ca193..c8c2f42 100644
--- a/client/src/pages/settings/GeneralSettings.tsx
+++ b/client/src/pages/settings/GeneralSettings.tsx
@@ -1,7 +1,7 @@
 import React from "react";
 import { useTranslate } from "@refinedev/core";
 import { Button, Form, Input, message } from "antd";
-import { useGetSettings, useSetSetting } from "./querySettings";
+import { useGetSettings, useSetSetting } from "../../utils/querySettings";
 
 export function GeneralSettings() {
   const settings = useGetSettings();
diff --git a/client/src/pages/spools/list.tsx b/client/src/pages/spools/list.tsx
index 714a6f8..eda7e16 100644
--- a/client/src/pages/spools/list.tsx
+++ b/client/src/pages/spools/list.tsx
@@ -52,7 +52,7 @@ function collapseSpool(element: ISpool): ISpoolCollapsed {
   } else {
     filament_name = element.filament.name ?? element.filament.id.toString();
   }
-  if (!element.price){
+  if (!element.price) {
     element.price = element.filament.price;
   }
   return {
@@ -306,6 +306,7 @@ export const SpoolList: React.FC<IResourceComponentsProps> = () => {
             tableState,
             dataId: "filament.id",
             filterValueQuery: useSpoolmanFilamentFilter(),
+            sorter: true,
           }),
           FilteredQueryColumn({
             id: "filament.material",
@@ -315,6 +316,7 @@ export const SpoolList: React.FC<IResourceComponentsProps> = () => {
             tableState,
             filterValueQuery: useSpoolmanMaterials(),
             width: 120,
+            sorter: true,
           }),
           SortedColumn({
             id: "price",
@@ -328,43 +330,47 @@ export const SpoolList: React.FC<IResourceComponentsProps> = () => {
             id: "used_weight",
             i18ncat: "spool",
             unit: "g",
-            decimals: 1,
+            maxDecimals: 1,
             actions,
             dataSource,
             tableState,
             width: 110,
+            sorter: true,
           }),
           NumberColumn({
             id: "remaining_weight",
             i18ncat: "spool",
             unit: "g",
-            decimals: 1,
+            maxDecimals: 1,
             defaultText: t("unknown"),
             actions,
             dataSource,
             tableState,
             width: 110,
+            sorter: true,
           }),
           NumberColumn({
             id: "used_length",
             i18ncat: "spool",
             unit: "mm",
-            decimals: 1,
+            maxDecimals: 1,
             actions,
             dataSource,
             tableState,
             width: 120,
+            sorter: true,
           }),
           NumberColumn({
             id: "remaining_length",
             i18ncat: "spool",
             unit: "mm",
-            decimals: 1,
+            maxDecimals: 1,
             defaultText: t("unknown"),
             actions,
             dataSource,
             tableState,
             width: 120,
+            sorter: true,
           }),
           FilteredQueryColumn({
             id: "location",
@@ -374,6 +380,7 @@ export const SpoolList: React.FC<IResourceComponentsProps> = () => {
             tableState,
             filterValueQuery: useSpoolmanLocations(),
             width: 120,
+            sorter: true,
           }),
           FilteredQueryColumn({
             id: "lot_nr",
@@ -383,6 +390,7 @@ export const SpoolList: React.FC<IResourceComponentsProps> = () => {
             tableState,
             filterValueQuery: useSpoolmanLotNumbers(),
             width: 120,
+            sorter: true,
           }),
           DateColumn({
             id: "first_used",
@@ -390,6 +398,7 @@ export const SpoolList: React.FC<IResourceComponentsProps> = () => {
             actions,
             dataSource,
             tableState,
+            sorter: true,
           }),
           DateColumn({
             id: "last_used",
@@ -397,6 +406,7 @@ export const SpoolList: React.FC<IResourceComponentsProps> = () => {
             actions,
             dataSource,
             tableState,
+            sorter: true,
           }),
           DateColumn({
             id: "registered",
@@ -404,6 +414,7 @@ export const SpoolList: React.FC<IResourceComponentsProps> = () => {
             actions,
             dataSource,
             tableState,
+            sorter: true,
           }),
           RichColumn({
             id: "comment",
@@ -412,6 +423,7 @@ export const SpoolList: React.FC<IResourceComponentsProps> = () => {
             dataSource,
             tableState,
             width: 150,
+            sorter: true,
           }),
           ActionsColumn(actions),
         ])}
diff --git a/client/src/pages/vendors/list.tsx b/client/src/pages/vendors/list.tsx
index e8615c2..50a87cb 100644
--- a/client/src/pages/vendors/list.tsx
+++ b/client/src/pages/vendors/list.tsx
@@ -152,6 +152,7 @@ export const VendorList: React.FC<IResourceComponentsProps> = () => {
             actions,
             dataSource,
             tableState,
+            sorter: true,
           }),
           RichColumn({
             id: "comment",
@@ -159,6 +160,7 @@ export const VendorList: React.FC<IResourceComponentsProps> = () => {
             actions,
             dataSource,
             tableState,
+            sorter: true,
           }),
           ActionsColumn<IVendor>(actions),
         ])}
diff --git a/client/src/pages/settings/queryFields.ts b/client/src/utils/queryFields.ts
similarity index 98%
rename from client/src/pages/settings/queryFields.ts
rename to client/src/utils/queryFields.ts
index 8ea0a43..d569278 100644
--- a/client/src/pages/settings/queryFields.ts
+++ b/client/src/utils/queryFields.ts
@@ -23,7 +23,7 @@ export interface FieldParameters {
   order: number;
   unit?: string;
   field_type: FieldType;
-  default_value?: string | boolean | dayjs.Dayjs;
+  default_value?: string | (number | null)[] | boolean | dayjs.Dayjs;
   choices?: string[];
   multi_choice?: boolean;
 }
diff --git a/client/src/pages/settings/querySettings.ts b/client/src/utils/querySettings.ts
similarity index 100%
rename from client/src/pages/settings/querySettings.ts
rename to client/src/utils/querySettings.ts
diff --git a/spoolman/extra_fields.py b/spoolman/extra_fields.py
index adb3847..ba773cc 100644
--- a/spoolman/extra_fields.py
+++ b/spoolman/extra_fields.py
@@ -73,8 +73,8 @@ def validate_extra_field_value(field: ExtraFieldParameters, value: str) -> None:
             raise ValueError("Value is not a list.")
         if len(data) != 2:  # noqa: PLR2004
             raise ValueError("Value list must have exactly two values.")
-        if not all(isinstance(value, int) for value in data):
-            raise ValueError("Value list must contain only integers.")
+        if not all(isinstance(value, int) or value is None for value in data):
+            raise ValueError("Value list must contain only integers or null.")
     elif field.field_type == ExtraFieldType.float:
         if not isinstance(data, (float, int)) or isinstance(data, bool):
             raise ValueError("Value is not a float.")
@@ -83,8 +83,10 @@ def validate_extra_field_value(field: ExtraFieldParameters, value: str) -> None:
             raise ValueError("Value is not a list.")
         if len(data) != 2:  # noqa: PLR2004
             raise ValueError("Value list must have exactly two values.")
-        if not all(isinstance(value, (float, int)) and not isinstance(value, bool) for value in data):
-            raise ValueError("Value list must contain only floats.")
+        if not all(
+            (isinstance(value, (float, int)) or value is None) and not isinstance(value, bool) for value in data
+        ):
+            raise ValueError("Value list must contain only floats or null.")
     elif field.field_type == ExtraFieldType.datetime:
         if not isinstance(data, str):
             raise ValueError("Value is not a string.")