Have had mixed results so far, having problems with the caps more than anything.
I'm picturing a male/female set of caps that fit snugly and into each other so they don't pop off so easy.
Am getting some friction, the material I am using is about .29 thick, the bearings .27, so I think the caps are rubbing the body a bit, causing short spin times.
Material I am using is the stuff they use at skating rinks for boards, helped a friend do a teardown of a rink and saved quite a bit of it. Is about 3/4" thick so I sliced it down to around .30, probably should have went a bit more.
Tried plexi mirror too, which is a bit thinner than the bearing. Too fragile for this purpose, probably too light too. So I'll keep at it until I get an acceptable design.