// --- 1/2" PVC CALIBRATION TRIO ---
$fn = 100;

pvc_12_od = 21.3; // Standard 1/2" Schedule 40 OD
wall = 4;
height = 10; 

// Offsets to test (Tighter range since we know your printer is accurate)
offsets = [0.05, 0.15, 0.25]; 

module test_ring_small(offset, index) {
    id = pvc_12_od + offset;
    od = id + (wall * 2);
    
    translate([index * (od + 10), 0, 0]) {
        difference() {
            cylinder(d = od, h = height);
            translate([0, 0, -1]) cylinder(d = id, h = height + 2);
            
            // Identification Notches
            for (n = [0 : index]) {
                rotate([0, 0, n * 20])
                translate([od/2, 0, height/2])
                cube([4, 2, height + 1], center=true);
            }
        }
    }
}

test_ring_small(offsets[0], 0); // 1 Notch  (0.05) - Tightest
test_ring_small(offsets[1], 1); // 2 Notches (0.15) - Snug
test_ring_small(offsets[2], 2); // 3 Notches (0.25) - Loose