I got the opportunity to test drive some of the flex-shaft size
wheels and they have lots of potential. They work well on the insides
of bracelets, and I would imagine on rings as well. The ones I tried
weren't marked, so I don't know what was what.
I have a little experience with the bigger ones as well, and I like
Kudos to 3M for their continuing push to develop new abrasives and
media. One that I like a LOT that I've never seen mentioned here are
the 1" pressure sensitive discs for the flexshaft. I use them more
than any other abrasive. They're exceptional for shaping and
smoothing. 3M used to make a little fixture for them called Rol-loc
that was great, but discontinued for some reason. But they still sell
another one (Rio,etc.) that works fine.