Magnetic nail spinner glass bead, 12mm & horseshoe

This model just need a single F695 bearing, and some 12x2mm magnets, or a large horseshoe magnet. Tolerances are fairly tight to prevent wobbling, so tweak your scaling if you find things don't fit correctly!

12mm magnet version

Load with 12x2mm magnets (two per hole) and an F695 bearing. You need a 50/50 mix of positive and negative facing magnets (e.g. left half all facing up, right half all facing down — other arrangements might also work!). You can use taller (e.g. 12x3mm) magnets instead if you prefer, but once you get above 4mm in total they'll stick out.

Horseshoe magnet version

A magnet will sit on top fairly stably on its own, pressed up against the divider that runs across the diameter. However a little Blutack on each side will keep it set in place if it wobbles.

Variations

There are two different base sizes included in the file — if you have small fingers, you can use the Short version to get the magnet a little closer to your nail. Or use the regular version for your thumb, and the short version for fingers.

This is the first working prototype, happy to make tweaks and variations if people let me know what they'd like. 

F695 bearings on Amazon: https://www.amazon.com/s?k=f695 Note that you don't need the rubber sealed (RS/2RS) variety, but they will work fine.

12x2mm magnets on Amazon: https://www.amazon.com/s?k=12x2mm+magnets