A 3D-Printed Watch Case With a Bayonet-Mount Back

Maker Z0hn set out to 3D print an entire watch case from scratch, and solved the one detail that trips up most printed-case builds: how to close the back.

What They Built

The project is a complete watch case, printable on an ordinary FDM machine, designed to hold a standard off-the-shelf Miyota 8N24 movement and a stock crystal. Rather than a high-end custom movement, the interesting part is entirely in the case design itself.

How They Did It

Printed threads and screw-down backs are notoriously unreliable on FDM printers — layer lines and dimensional tolerances make fine threads gritty or loose, and they tend to strip out over repeated opening and closing. Z0hn’s case sidesteps the problem with a bayonet-style twist-lock back instead: a quarter-turn connector that’s far more forgiving to print accurately and holds up better to daily handling than threaded alternatives. The rest of the design is built to be easy to modify, with details like crown placement left open for makers to adapt to their own movement or wrist preferences.

Go See It

Z0hn published the full build on Instructables as “Building Your Own Custom Watch From Scratch,” a step-by-step guide covering the case design and assembly. Hackaday featured the project on June 13, 2026.