This bracelet uses a magnetic clasp which closes flush so it won't catch on anything...

Customizer included, but example shown uses a 2.8mm diameter nail (cut to length) and 6x2.5mm cylindrical magnets. Scale for size or fully customize fit using OpenSCAD.

It's not too hard to separate (give it a whack) if printed as is, or split shells and use supports. Use a drill to clean out the hole so the nail slides freely before inserting magnet which can be secured by a drop of superglue.

Use another magnet to remove the pin (I was tempted to leave that as an exercise for the reader to figure out). Embed the “key” in another model if you're feeling creative.