Customizable Hinged Box | Print-in-Place Snap Lid

Customizable: the OpenSCAD source (.scad) is in the files. Open it in the free OpenSCAD app and use its Customizer panel (Window - Customizer) - that is what "Customize" refers to below.

A box with a hinged lid that comes off the printer already assembled. No pins, no glue, no supports: print it, fold the lid over, and it snaps shut.

How it prints. The box stands upright; the lid lies upside down right behind it, opened flat, joined by the hinge. The hinge axis sits exactly halfway between the box height and the lid height, so the flipped lid lands top-down on the bed. The top of the lid is the side that touched the bed, so it comes out smooth.

The hinge. Five knuckles (box, lid, box, lid, box). The box knuckles carry cone-shaped pins that point into cone sockets in the lid knuckles, with a 0.4 mm gap all around. The cone flanks are 40 degrees from vertical underneath, so they print over the gap without supports, and the lid knuckles are trapped between the box knuckles: the lid cannot be pulled off.

The latch. A tongue hangs from the front of the lid; a hook on its tip snaps under a ridge on the box. A small lip on the tongue tip lets you flick it open with a fingernail.

Files in the download: 60x40x30, 100x70x40 and 150x100x50 mm (inside length x width x depth of the box body), plus 100x70x40 with 6 cells and 150x100x50 with 12 cells. Anything else: Customize.

Customize (the .scad is included):

• Size: presets or your own inside length 30–200, width 30–110, depth 15–150 mm; lid height
• Walls: wall and floor thickness, corner radius
• Hinge: clearance 0.3–0.5 mm (default 0.4), 3–9 knuckles, knuckle diameter
• Latch on/off, width, length, tongue thickness, snap depth
• Dividers: up to 9 across the length and 5 across the width
• It refuses settings that would not work: a lid as tall as the box, a box + open lid wider than a 250 mm bed, knuckles too short for the cone sockets, a latch that does not fit, too many dividers. Width is capped at 110 mm because the open lid prints next to the box.

Numbers (checked on the STL files):

• Printed layout: the box and the lid never touch; smallest gap 0.40 mm.
• The lid was swung through the full 180 degrees in 0.5-degree steps against the box: no collision anywhere. The only contact is the hook passing the ridge in the last 1–2.5 degrees before it closes; the tongue bends 0.74–0.80 mm to snap (about 1.7 % strain at its root).
• Closed: lid resting on the rim, hook under the ridge with 0.3 mm play.
• On the printer the lid can move at most 0.62 mm in any direction before it hits the box knuckles: it is captured.

Print time / filament (Bambu Studio, P2S, 0.20 mm, PLA): 60x40x30 49 min / 36.6 g, 100x70x40 1 h 36 min / 83.7 g, 150x100x50 2 h 45 min / 158.1 g, 100x70x40 with dividers 1 h 57 min / 101.6 g, 150x100x50 grid 3 h 50 min / 214.0 g.

Prints without supports. Measured on the mesh: 0 mm² of surface steeper than 45 degrees on every file, and the slicer generated no supports.

PRINT SETTINGS: PLA or PETG, 0.20 mm layers, 0.4 mm nozzle, 3 walls, 15 % infill, supports OFF, brim not needed. Keep the first layer well calibrated (no elephant foot) — the hinge gaps start 0.3 mm above the bed. After printing, open and close the lid a few times to free the hinge. If your printer over-extrudes, set hinge_clearance to 0.45–0.5 in Customize.

Honest notes

• Not test-printed yet. Fits and motion come from measuring the STL files (boolean checks while rotating the lid), not from a printed box.
• The file contains two separate bodies, box and lid, linked by the hinge. That is intended for print-in-place; do not "split to objects" or move them apart in the slicer.
• The latch tongue stands upright on the printer, so when it snaps it bends across the layers — the weak direction of a print. 1.7 % strain is fine on paper but may crack a brittle PLA print at the root; PETG is safer, or lower latch_snap in Customize.
• The lid sits on the rim without an inner lip: it keeps dust out, it is not watertight.
• On tall boxes with a low lid the latch cannot work (the tongue swings into the box); the file then asks you to raise the lid or switch the latch off.
• The pictures are 3D renders made from the same files.