How to design an electronics enclosure that works first time
Wall thicknesses, board standoffs, connector clearances and ventilation. The concrete numbers so the box closes and the board sits still.
Almost every enclosure we receive fails the same way: it was drawn to the nominal dimensions of the board and the connectors. Plastic shrinks, the nozzle rounds off inside corners, and the box ends up half a millimetre small exactly where it should not be. These are the allowances we use.
1. Start with the wall thickness
- 1.6 mm — the default for a box that gets picked up.
- 2.0 to 2.4 mm — wall-mounted, in a workshop, or taking knocks.
- 1.2 mm — only for form prototypes nobody will actually use.
2. Standoffs, not screws into plastic
PCB holes are usually 3.2 mm for an M3. Draw the standoff with a 4.2 mm hole and press in a brass M3 threaded insert: the screw bites into metal and you can open the box as often as you like. Tap the plastic directly and the thread strips by the fourth or fifth assembly.
3. Connector clearances
| Feature | Allowance per side |
|---|---|
| USB, HDMI, jack cut-out | +0.4 mm |
| Through hole for a 5 mm LED | +0.3 mm |
| Board pocket (outline) | +0.5 mm |
| Press-fit lid | +0.15 mm |
| Sliding lid | +0.3 mm |
4. Heat: the box is a thermos
A sealed plastic box dumps no heat. If there is more than 2 or 3 W running inside, slot two opposite faces so air can move, and choose PETG or ABS over PLA. A regulator sitting at 60 °C will soften a PLA box until it deforms.
Finally, orient with the seam in mind
We print the box open-side up whenever we can: the walls then need no supports and the visible surfaces stay smooth. If your design forces something else, we spot it before printing and tell you.