A spinning Mietha keychain: a logo disc that turns inside its ring

A logo keychain for the duo Mietha that is not just another flat tag, because it spins: the logo disc sits on two pins inside a ring with a keyring eye and turns with a flick of a finger. Both parts print together, assembled, with no supports and no assembly. From a flat logo to version v11 in under a month, then a run from plates of 25.

IE-033 · FIG.01 · Render from the CAD model (Blender). The same keychain with the disc at four positions: 0°, 30°, 60° and 90°.

Problem

The Mietha logo is a hand-drawn M with an arrow: thin, open strokes that have to hold up at 4 mm thickness so the keychain does not snap in a pocket. The spinning version adds a gap between the disc and the ring: too tight and the print fuses into one solid, too loose and the disc wobbles instead of spinning. On top of that it is a run, so every piece off the plate has to turn straight away, with no fiddling.

Outcome

A logo keychain that spins instead of just hanging there. The run came off the printer finished: no supports to strip, no glue, no assembly. We keep the v11 model and the plate file, so a reprint is one plate away, and the same mechanism takes any other logo.

01First test in October: a flat teardrop tag, black with a green logo. It worked, but looked like any other giveaway.
02The logo as a solid: an open M with an arrow and a keyring eye, 40.7 x 55.5 x 4 mm (v1 and v3). In parallel, cleaning up the logo files: AI and DWG vectors for the model.
03The spinning version in Shapr3D: a ring with a keyring eye and a ⌀36.4 mm logo disc on two pins on a vertical axis. The smallest gap between the parts is 0.24 mm, tuned with test prints so the disc neither fuses nor wobbles.
04Printed in one piece, flat and without supports: Bambu Lab P1S, PLA, 0.16 mm layers, full infill to stiffen the thin strokes. 25 keychains on one plate.
05Off the plate, a key ring on and a test between the fingers: one flick should set the disc spinning.