diff --git a/tests_integration/tests/conftest.py b/tests_integration/tests/conftest.py
index abe7130..51e3e97 100644
--- a/tests_integration/tests/conftest.py
+++ b/tests_integration/tests/conftest.py
@@ -1,12 +1,15 @@
 """Test fixtures for integration tests."""
 
 import time
+from typing import Any
 
 import httpx
 import pytest
 
 TIMEOUT = 10
 
+URL = "http://spoolman:8000"
+
 
 @pytest.fixture(scope="session", autouse=True)
 def _wait_for_server():  # noqa: ANN202
@@ -21,3 +24,48 @@ def _wait_for_server():  # noqa: ANN202
                 raise
         else:
             break
+
+
+@pytest.fixture()
+def random_vendor():
+    """Return a random vendor."""
+    # Add vendor
+    result = httpx.post(
+        f"{URL}/api/v1/vendor",
+        json={"name": "John"},
+    )
+    result.raise_for_status()
+
+    vendor = result.json()
+    yield vendor
+
+    # Delete vendor
+    httpx.delete(f"{URL}/api/v1/vendor/{vendor['id']}").raise_for_status()
+
+
+@pytest.fixture()
+def random_filament(random_vendor: dict[str, Any]):
+    """Return a random filament."""
+    # Add filament
+    result = httpx.post(
+        f"{URL}/api/v1/filament",
+        json={
+            "name": "Filament X",
+            "vendor_id": random_vendor["id"],
+            "material": "PLA",
+            "price": 100,
+            "density": 1.25,
+            "diameter": 1.75,
+            "weight": 1000,
+            "spool_weight": 250,
+            "article_number": "123456789",
+            "comment": "abcdefghåäö",
+        },
+    )
+    result.raise_for_status()
+
+    filament = result.json()
+    yield filament
+
+    # Delete filament
+    httpx.delete(f"{URL}/api/v1/filament/{filament['id']}").raise_for_status()
diff --git a/tests_integration/tests/test_filament.py b/tests_integration/tests/test_filament.py
new file mode 100644
index 0000000..f8a2bdf
--- /dev/null
+++ b/tests_integration/tests/test_filament.py
@@ -0,0 +1,363 @@
+"""Integration tests for the Filament API endpoint."""
+
+from typing import Any
+
+import httpx
+
+URL = "http://spoolman:8000"
+
+
+def test_add_filament(random_vendor: dict[str, Any]):
+    """Test adding a filament to the database."""
+    # Execute
+    name = "Filament X"
+    material = "PLA"
+    price = 100
+    density = 1.25
+    diameter = 1.75
+    weight = 1000
+    spool_weight = 250
+    article_number = "123456789"
+    comment = "abcdefghåäö"
+    result = httpx.post(
+        f"{URL}/api/v1/filament",
+        json={
+            "name": name,
+            "vendor_id": random_vendor["id"],
+            "material": material,
+            "price": price,
+            "density": density,
+            "diameter": diameter,
+            "weight": weight,
+            "spool_weight": spool_weight,
+            "article_number": article_number,
+            "comment": comment,
+        },
+    )
+    result.raise_for_status()
+
+    # Verify
+    filament = result.json()
+    assert filament["name"] == name
+    assert filament["vendor"] == random_vendor
+    assert filament["material"] == material
+    assert filament["price"] == price
+    assert filament["density"] == density
+    assert filament["diameter"] == diameter
+    assert filament["weight"] == weight
+    assert filament["spool_weight"] == spool_weight
+    assert filament["article_number"] == article_number
+    assert filament["comment"] == comment
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/filament/{filament['id']}").raise_for_status()
+
+
+def test_get_filament(random_vendor: dict[str, Any]):
+    """Test getting a filament from the database."""
+    # Setup
+    name = "Filament X"
+    material = "PLA"
+    price = 100
+    density = 1.25
+    diameter = 1.75
+    weight = 1000
+    spool_weight = 250
+    article_number = "123456789"
+    comment = "abcdefghåäö"
+    result = httpx.post(
+        f"{URL}/api/v1/filament",
+        json={
+            "name": name,
+            "vendor_id": random_vendor["id"],
+            "material": material,
+            "price": price,
+            "density": density,
+            "diameter": diameter,
+            "weight": weight,
+            "spool_weight": spool_weight,
+            "article_number": article_number,
+            "comment": comment,
+        },
+    )
+    result.raise_for_status()
+    added_filament = result.json()
+
+    # Execute
+    result = httpx.get(
+        f"{URL}/api/v1/filament/{added_filament['id']}",
+    )
+    result.raise_for_status()
+
+    # Verify
+    filament = result.json()
+    assert filament["name"] == name
+    assert filament["vendor"] == random_vendor
+    assert filament["material"] == material
+    assert filament["price"] == price
+    assert filament["density"] == density
+    assert filament["diameter"] == diameter
+    assert filament["weight"] == weight
+    assert filament["spool_weight"] == spool_weight
+    assert filament["article_number"] == article_number
+    assert filament["comment"] == comment
+    assert filament["id"] == added_filament["id"]
+    assert filament["registered"] == added_filament["registered"]
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/filament/{filament['id']}").raise_for_status()
+
+
+def test_get_filament_not_found():
+    """Test getting a filament that does not exist."""
+    # Execute
+    result = httpx.get(
+        f"{URL}/api/v1/filament/123456789",
+    )
+
+    # Verify
+    assert result.status_code == 404
+
+
+def test_find_filaments(random_vendor: dict[str, Any]):
+    """Test finding filaments from the database."""
+    # Setup
+    result = httpx.post(
+        f"{URL}/api/v1/filament",
+        json={
+            "name": "Filament X",
+            "vendor_id": random_vendor["id"],
+            "material": "PLA",
+            "price": 100,
+            "density": 1.25,
+            "diameter": 1.75,
+            "weight": 1000,
+            "spool_weight": 250,
+            "article_number": "123456789",
+            "comment": "abcdefghåäö",
+        },
+    )
+    result.raise_for_status()
+    filament_1 = result.json()
+
+    result = httpx.post(
+        f"{URL}/api/v1/filament",
+        json={
+            "name": "Filament Y",
+            "vendor_id": random_vendor["id"],
+            "material": "ABS",
+            "price": 200,
+            "density": 1.25,
+            "diameter": 1.75,
+            "weight": 1000,
+            "spool_weight": 250,
+            "article_number": "987654321",
+            "comment": "abcdefghåäö",
+        },
+    )
+    result.raise_for_status()
+    filament_2 = result.json()
+
+    added_filaments_by_id = {
+        filament_1["id"]: filament_1,
+        filament_2["id"]: filament_2,
+    }
+
+    # Execute - find all filaments
+    result = httpx.get(
+        f"{URL}/api/v1/filament",
+    )
+    result.raise_for_status()
+
+    # Verify
+    filaments = result.json()
+    assert len(filaments) == 2
+    for filament in filaments:
+        assert filament == added_filaments_by_id[filament["id"]]
+
+    # Execute - find filaments by name
+    result = httpx.get(
+        f"{URL}/api/v1/filament",
+        params={"name": "Filament X"},
+    )
+    result.raise_for_status()
+
+    # Verify
+    filaments = result.json()
+    assert len(filaments) == 1
+    assert filaments[0] == added_filaments_by_id[filament_1["id"]]
+
+    # Execute - find filaments by material
+    result = httpx.get(
+        f"{URL}/api/v1/filament",
+        params={"material": "abs"},
+    )
+    result.raise_for_status()
+
+    # Verify
+    filaments = result.json()
+    assert len(filaments) == 1
+    assert filaments[0] == added_filaments_by_id[filament_2["id"]]
+
+    # Execute - find filaments by vendor id
+    result = httpx.get(
+        f"{URL}/api/v1/filament",
+        params={"vendor_id": random_vendor["id"]},
+    )
+    result.raise_for_status()
+
+    # Verify
+    filaments = result.json()
+    assert len(filaments) == 2
+    for filament in filaments:
+        assert filament == added_filaments_by_id[filament["id"]]
+
+    # Execute - find filaments by vendor name
+    result = httpx.get(
+        f"{URL}/api/v1/filament",
+        params={"vendor_name": random_vendor["name"]},
+    )
+    result.raise_for_status()
+
+    # Verify
+    filaments = result.json()
+    assert len(filaments) == 2
+    for filament in filaments:
+        assert filament == added_filaments_by_id[filament["id"]]
+
+    # Execute - find filaments by article number
+    result = httpx.get(
+        f"{URL}/api/v1/filament",
+        params={"article_number": "321"},
+    )
+    result.raise_for_status()
+
+    # Verify
+    filaments = result.json()
+    assert len(filaments) == 1
+    assert filaments[0] == added_filaments_by_id[filament_2["id"]]
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/filament/{filament_1['id']}").raise_for_status()
+    httpx.delete(f"{URL}/api/v1/filament/{filament_2['id']}").raise_for_status()
+
+
+def test_delete_filament(random_vendor: dict[str, Any]):
+    """Test deleting a filament from the database."""
+    # Setup
+    result = httpx.post(
+        f"{URL}/api/v1/filament",
+        json={
+            "name": "Filament X",
+            "vendor_id": random_vendor["id"],
+            "material": "PLA",
+            "price": 100,
+            "density": 1.25,
+            "diameter": 1.75,
+            "weight": 1000,
+            "spool_weight": 250,
+            "article_number": "123456789",
+            "comment": "abcdefghåäö",
+        },
+    )
+    result.raise_for_status()
+    added_filament = result.json()
+
+    # Execute
+    httpx.delete(
+        f"{URL}/api/v1/filament/{added_filament['id']}",
+    ).raise_for_status()
+
+    # Verify
+    result = httpx.get(
+        f"{URL}/api/v1/filament/{added_filament['id']}",
+    )
+    assert result.status_code == 404
+
+
+def test_delete_filament_not_found():
+    """Test deleting a filament that does not exist."""
+    # Execute
+    result = httpx.delete(f"{URL}/api/v1/filament/123456789")
+
+    # Verify
+    assert result.status_code == 404
+
+
+def test_update_filament(random_vendor: dict[str, Any]):
+    """Test updating a filament in the database."""
+    # Setup
+    result = httpx.post(
+        f"{URL}/api/v1/filament",
+        json={
+            "name": "Filament X",
+            "vendor_id": random_vendor["id"],
+            "material": "PLA",
+            "price": 100,
+            "density": 1.25,
+            "diameter": 1.75,
+            "weight": 1000,
+            "spool_weight": 250,
+            "article_number": "123456789",
+            "comment": "abcdefghåäö",
+        },
+    )
+    result.raise_for_status()
+    added_filament = result.json()
+
+    # Execute
+    new_name = "Filament Y"
+    new_material = "ABS"
+    new_price = 200
+    new_density = 4.2
+    new_diameter = 0.12
+    new_weight = 5431
+    new_spool_weight = 123
+    new_article_number = "987654321"
+    new_comment = "test"
+    result = httpx.patch(
+        f"{URL}/api/v1/filament/{added_filament['id']}",
+        json={
+            "name": new_name,
+            "vendor_id": random_vendor["id"],
+            "material": new_material,
+            "price": new_price,
+            "density": new_density,
+            "diameter": new_diameter,
+            "weight": new_weight,
+            "spool_weight": new_spool_weight,
+            "article_number": new_article_number,
+            "comment": new_comment,
+        },
+    )
+    result.raise_for_status()
+
+    # Verify
+    filament = result.json()
+    assert filament["name"] == new_name
+    assert filament["vendor"] == random_vendor
+    assert filament["material"] == new_material
+    assert filament["price"] == new_price
+    assert filament["density"] == new_density
+    assert filament["diameter"] == new_diameter
+    assert filament["weight"] == new_weight
+    assert filament["spool_weight"] == new_spool_weight
+    assert filament["article_number"] == new_article_number
+    assert filament["comment"] == new_comment
+    assert filament["id"] == added_filament["id"]
+    assert filament["registered"] == added_filament["registered"]
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/filament/{filament['id']}").raise_for_status()
+
+
+def test_update_filament_not_found():
+    """Test updating a filament that does not exist."""
+    # Execute
+    result = httpx.patch(
+        f"{URL}/api/v1/filament/123456789",
+        json={"name": "Filament Y"},
+    )
+
+    # Verify
+    assert result.status_code == 404
diff --git a/tests_integration/tests/test_spool.py b/tests_integration/tests/test_spool.py
new file mode 100644
index 0000000..fbbd436
--- /dev/null
+++ b/tests_integration/tests/test_spool.py
@@ -0,0 +1,495 @@
+"""Integration tests for the Spool API endpoint."""
+
+import math
+from typing import Any
+
+import httpx
+import pytest
+
+URL = "http://spoolman:8000"
+
+
+def test_add_spool_remaining_weight(random_filament: dict[str, Any]):
+    """Test adding a spool to the database."""
+    # Execute
+    first_used = "2023-01-01T00:00:00"
+    last_used = "2023-01-02T00:00:00"
+    remaining_weight = 750
+    location = "The Pantry"
+    lot_nr = "123456789"
+    comment = "abcdefghåäö"
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={
+            "first_used": first_used,
+            "last_used": last_used,
+            "filament_id": random_filament["id"],
+            "remaining_weight": remaining_weight,
+            "location": location,
+            "lot_nr": lot_nr,
+            "comment": comment,
+        },
+    )
+    result.raise_for_status()
+
+    # Verify
+    spool = result.json()
+    assert spool["first_used"] == first_used
+    assert spool["last_used"] == last_used
+    assert spool["filament"] == random_filament
+    assert spool["remaining_weight"] == pytest.approx(remaining_weight)
+    assert spool["used_weight"] == pytest.approx(random_filament["weight"] - remaining_weight)
+    assert spool["location"] == location
+    assert spool["lot_nr"] == lot_nr
+    assert spool["comment"] == comment
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/spool/{spool['id']}").raise_for_status()
+
+
+def test_add_spool_used_weight(random_filament: dict[str, Any]):
+    """Test adding a spool to the database."""
+    # Execute
+    first_used = "2023-01-01T00:00:00"
+    last_used = "2023-01-02T00:00:00"
+    used_weight = 250
+    location = "The Pantry"
+    lot_nr = "123456789"
+    comment = "abcdefghåäö"
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={
+            "first_used": first_used,
+            "last_used": last_used,
+            "filament_id": random_filament["id"],
+            "used_weight": used_weight,
+            "location": location,
+            "lot_nr": lot_nr,
+            "comment": comment,
+        },
+    )
+    result.raise_for_status()
+
+    # Verify
+    spool = result.json()
+    assert spool["first_used"] == first_used
+    assert spool["last_used"] == last_used
+    assert spool["filament"] == random_filament
+    assert spool["remaining_weight"] == pytest.approx(random_filament["weight"] - used_weight)
+    assert spool["used_weight"] == pytest.approx(used_weight)
+    assert spool["location"] == location
+    assert spool["lot_nr"] == lot_nr
+    assert spool["comment"] == comment
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/spool/{spool['id']}").raise_for_status()
+
+
+def test_add_spool_both_used_and_remaining_weight(random_filament: dict[str, Any]):
+    """Test adding a spool to the database."""
+    # Execute
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={
+            "filament_id": random_filament["id"],
+            "remaining_weight": 750,
+            "used_weight": 250,
+        },
+    )
+    assert result.status_code == 400  # Cannot set both used and remaining weight
+
+
+def test_get_spool(random_filament: dict[str, Any]):
+    """Test getting a spool from the database."""
+    # Setup
+    first_used = "2023-01-01T00:00:00"
+    last_used = "2023-01-02T00:00:00"
+    remaining_weight = 750
+    location = "The Pantry"
+    lot_nr = "123456789"
+    comment = "abcdefghåäö"
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={
+            "first_used": first_used,
+            "last_used": last_used,
+            "filament_id": random_filament["id"],
+            "remaining_weight": remaining_weight,
+            "location": location,
+            "lot_nr": lot_nr,
+            "comment": comment,
+        },
+    )
+    result.raise_for_status()
+    spool = result.json()
+
+    # Execute
+    result = httpx.get(f"{URL}/api/v1/spool/{spool['id']}")
+    result.raise_for_status()
+
+    # Verify
+    assert result.json() == spool
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/spool/{spool['id']}").raise_for_status()
+
+
+def test_get_spool_not_found():
+    """Test getting a spool that does not exist."""
+    # Execute
+    result = httpx.get(f"{URL}/api/v1/spool/123456789")
+
+    # Verify
+    assert result.status_code == 404
+
+
+def test_find_spools(random_filament: dict[str, Any]):  # noqa: PLR0915
+    """Test finding spools in the database."""
+    # Setup
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={
+            "filament_id": random_filament["id"],
+            "remaining_weight": 1000,
+            "location": "The Pantry",
+            "lot_nr": "123456789",
+        },
+    )
+    result.raise_for_status()
+    spool_1 = result.json()
+
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={
+            "filament_id": random_filament["id"],
+            "remaining_weight": 1000,
+            "location": "Living Room",
+            "lot_nr": "987654321",
+        },
+    )
+    result.raise_for_status()
+    spool_2 = result.json()
+
+    added_spools_by_id = {
+        spool_1["id"]: spool_1,
+        spool_2["id"]: spool_2,
+    }
+
+    # Execute - find all spools
+    result = httpx.get(f"{URL}/api/v1/spool")
+    result.raise_for_status()
+
+    # Verify
+    spools = result.json()
+    assert len(spools) == 2
+    for spool in spools:
+        assert spool == added_spools_by_id[spool["id"]]
+
+    # Execute - find spools by filament name
+    result = httpx.get(
+        f"{URL}/api/v1/spool",
+        params={"filament_name": random_filament["name"]},
+    )
+    result.raise_for_status()
+
+    # Verify
+    spools = result.json()
+    assert len(spools) == 2
+    for spool in spools:
+        assert spool == added_spools_by_id[spool["id"]]
+
+    # Execute - find spools by filament id
+    result = httpx.get(
+        f"{URL}/api/v1/spool",
+        params={"filament_id": random_filament["id"]},
+    )
+    result.raise_for_status()
+
+    # Verify
+    spools = result.json()
+    assert len(spools) == 2
+    for spool in spools:
+        assert spool == added_spools_by_id[spool["id"]]
+
+    # Execute - find spools by filament material
+    result = httpx.get(
+        f"{URL}/api/v1/spool",
+        params={"filament_material": random_filament["material"]},
+    )
+    result.raise_for_status()
+
+    # Verify
+    spools = result.json()
+    assert len(spools) == 2
+    for spool in spools:
+        assert spool == added_spools_by_id[spool["id"]]
+
+    # Execute - find spools by filament vendor name
+    result = httpx.get(
+        f"{URL}/api/v1/spool",
+        params={"vendor_name": random_filament["vendor"]["name"]},
+    )
+    result.raise_for_status()
+
+    # Verify
+    spools = result.json()
+    assert len(spools) == 2
+    for spool in spools:
+        assert spool == added_spools_by_id[spool["id"]]
+
+    # Execute - find spools by filament vendor id
+    result = httpx.get(
+        f"{URL}/api/v1/spool",
+        params={"vendor_id": random_filament["vendor"]["id"]},
+    )
+    result.raise_for_status()
+
+    # Verify
+    spools = result.json()
+    assert len(spools) == 2
+    for spool in spools:
+        assert spool == added_spools_by_id[spool["id"]]
+
+    # Execute - find spools by location
+    result = httpx.get(
+        f"{URL}/api/v1/spool",
+        params={"location": "The Pantry"},
+    )
+    result.raise_for_status()
+
+    # Verify
+    spools = result.json()
+    assert len(spools) == 1
+    assert spools[0] == added_spools_by_id[spool_1["id"]]
+
+    # Execute - find spools by lot nr
+    result = httpx.get(
+        f"{URL}/api/v1/spool",
+        params={"lot_nr": "123456789"},
+    )
+    result.raise_for_status()
+
+    # Verify
+    spools = result.json()
+    assert len(spools) == 1
+    assert spools[0] == added_spools_by_id[spool_1["id"]]
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/spool/{spool_1['id']}").raise_for_status()
+    httpx.delete(f"{URL}/api/v1/spool/{spool_2['id']}").raise_for_status()
+
+
+def test_delete_spool(random_filament: dict[str, Any]):
+    """Test deleting a spool from the database."""
+    # Setup
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={
+            "filament_id": random_filament["id"],
+            "remaining_weight": 1000,
+            "location": "The Pantry",
+            "lot_nr": "123456789",
+        },
+    )
+    result.raise_for_status()
+    spool = result.json()
+
+    # Execute
+    httpx.delete(f"{URL}/api/v1/spool/{spool['id']}").raise_for_status()
+
+    # Verify
+    result = httpx.get(f"{URL}/api/v1/spool/{spool['id']}")
+    assert result.status_code == 404
+
+
+def test_delete_spool_not_found():
+    """Test deleting a spool that does not exist."""
+    # Execute
+    result = httpx.delete(f"{URL}/api/v1/spool/123456789")
+
+    # Verify
+    assert result.status_code == 404
+
+
+def test_update_spool(random_filament: dict[str, Any]):
+    """Test updating a spool in the database."""
+    # Setup
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={
+            "filament_id": random_filament["id"],
+            "remaining_weight": 1000,
+            "location": "The Pantry",
+            "lot_nr": "123456789",
+        },
+    )
+    result.raise_for_status()
+    spool = result.json()
+
+    # Execute
+    first_used = "2023-01-01T00:00:00"
+    last_used = "2023-01-02T00:00:00"
+    remaining_weight = 750
+    location = "Living Room"
+    lot_nr = "987654321"
+    comment = "abcdefghåäö"
+    result = httpx.patch(
+        f"{URL}/api/v1/spool/{spool['id']}",
+        json={
+            "first_used": first_used,
+            "last_used": last_used,
+            "remaining_weight": remaining_weight,
+            "location": location,
+            "lot_nr": lot_nr,
+            "comment": comment,
+        },
+    )
+    result.raise_for_status()
+
+    # Verify
+    spool = result.json()
+    assert spool["first_used"] == first_used
+    assert spool["last_used"] == last_used
+    assert spool["remaining_weight"] == pytest.approx(remaining_weight)
+    assert spool["used_weight"] == pytest.approx(random_filament["weight"] - remaining_weight)
+    assert spool["location"] == location
+    assert spool["lot_nr"] == lot_nr
+    assert spool["comment"] == comment
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/spool/{spool['id']}").raise_for_status()
+
+
+def test_update_spool_both_used_and_remaining_weight(random_filament: dict[str, Any]):
+    """Test updating a spool in the database."""
+    # Setup
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={"filament_id": random_filament["id"]},
+    )
+    result.raise_for_status()
+    spool = result.json()
+
+    # Execute
+    result = httpx.patch(
+        f"{URL}/api/v1/spool/{spool['id']}",
+        json={
+            "remaining_weight": 750,
+            "used_weight": 250,
+        },
+    )
+    assert result.status_code == 400  # Cannot update both used and remaining weight
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/spool/{spool['id']}").raise_for_status()
+
+
+def test_update_spool_not_found(random_filament: dict[str, Any]):
+    """Test updating a spool that does not exist."""
+    # Execute
+    result = httpx.patch(
+        f"{URL}/api/v1/spool/123456789",
+        json={"filament_id": random_filament["id"]},
+    )
+    assert result.status_code == 404
+
+
+def test_use_spool_weight(random_filament: dict[str, Any]):
+    """Test using a spool in the database."""
+    # Setup
+    start_weight = 1000
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={
+            "filament_id": random_filament["id"],
+            "remaining_weight": start_weight,
+        },
+    )
+    result.raise_for_status()
+    spool = result.json()
+
+    # Execute
+    used_weight = 0.05
+    result = httpx.put(
+        f"{URL}/api/v1/spool/{spool['id']}/use",
+        json={
+            "use_weight": used_weight,
+        },
+    )
+    result.raise_for_status()
+
+    # Verify
+    spool = result.json()
+    assert spool["remaining_weight"] == pytest.approx(start_weight - used_weight)
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/spool/{spool['id']}").raise_for_status()
+
+
+def test_use_spool_length(random_filament: dict[str, Any]):
+    """Test using a spool in the database."""
+    # Setup
+    start_weight = 1000
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={
+            "filament_id": random_filament["id"],
+            "remaining_weight": start_weight,
+        },
+    )
+    result.raise_for_status()
+    spool = result.json()
+
+    # Execute
+    used_length = 10  # mm
+    result = httpx.put(
+        f"{URL}/api/v1/spool/{spool['id']}/use",
+        json={
+            "use_length": used_length,
+        },
+    )
+    result.raise_for_status()
+
+    # Verify
+    spool = result.json()
+    used_weight = (
+        random_filament["density"] * (used_length * 1e-1) * math.pi * ((random_filament["diameter"] * 1e-1 / 2) ** 2)
+    )
+    assert spool["remaining_weight"] == pytest.approx(start_weight - used_weight)
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/spool/{spool['id']}").raise_for_status()
+
+
+def test_use_spool_weight_and_length(random_filament: dict[str, Any]):
+    """Test using a spool in the database."""
+    # Setup
+    result = httpx.post(
+        f"{URL}/api/v1/spool",
+        json={"filament_id": random_filament["id"]},
+    )
+    result.raise_for_status()
+    spool = result.json()
+
+    # Execute
+    result = httpx.put(
+        f"{URL}/api/v1/spool/{spool['id']}/use",
+        json={
+            "use_weight": 0.05,
+            "use_length": 10,
+        },
+    )
+    assert result.status_code == 400  # Cannot use both weight and length
+
+    # Clean up
+    httpx.delete(f"{URL}/api/v1/spool/{spool['id']}").raise_for_status()
+
+
+def test_use_spool_not_found():
+    """Test using a spool that does not exist."""
+    # Execute
+    result = httpx.put(
+        f"{URL}/api/v1/spool/123456789/use",
+        json={"use_weight": 0.05},
+    )
+    assert result.status_code == 404
diff --git a/tests_integration/tests/test_api.py b/tests_integration/tests/test_vendor.py
similarity index 84%
rename from tests_integration/tests/test_api.py
rename to tests_integration/tests/test_vendor.py
index 1250abb..f3a7e7c 100644
--- a/tests_integration/tests/test_api.py
+++ b/tests_integration/tests/test_vendor.py
@@ -1,4 +1,4 @@
-"""Integration tests for the API."""
+"""Integration tests for the Vendor API endpoint."""
 
 import httpx
 
@@ -56,6 +56,15 @@ def test_get_vendor():
     httpx.delete(f"{URL}/api/v1/vendor/{vendor['id']}").raise_for_status()
 
 
+def test_get_vendor_not_found():
+    """Test getting a vendor that does not exist."""
+    # Execute
+    result = httpx.get(f"{URL}/api/v1/vendor/123456789")
+
+    # Verify
+    assert result.status_code == 404
+
+
 def test_find_vendors():
     """Test finding vendors from the database."""
     # Setup
@@ -93,11 +102,7 @@ def test_find_vendors():
     assert len(vendors) == 2
 
     for vendor in vendors:
-        added_vendor = added_vendors_by_id[vendor["id"]]
-        assert vendor["name"] == added_vendor["name"]
-        assert vendor["comment"] == added_vendor["comment"]
-        assert vendor["id"] == added_vendor["id"]
-        assert vendor["registered"] == added_vendor["registered"]
+        assert vendor == added_vendors_by_id[vendor["id"]]
 
     # Execute - Find a specific vendor
     result = httpx.get(
@@ -146,6 +151,15 @@ def test_delete_vendor():
     assert result.status_code == 404
 
 
+def test_delete_vendor_not_found():
+    """Test deleting a vendor that does not exist."""
+    # Execute
+    result = httpx.delete(f"{URL}/api/v1/vendor/123456789")
+
+    # Verify
+    assert result.status_code == 404
+
+
 def test_update_vendor():
     """Test update a vendor in the database."""
     # Setup
@@ -176,3 +190,12 @@ def test_update_vendor():
 
     # Clean up
     httpx.delete(f"{URL}/api/v1/vendor/{vendor['id']}").raise_for_status()
+
+
+def test_update_vendor_not_found():
+    """Test updating a vendor that does not exist."""
+    # Execute
+    result = httpx.patch(f"{URL}/api/v1/vendor/123456789", json={"name": "John"})
+
+    # Verify
+    assert result.status_code == 404