[Zeke]

Try various Scotchbrite grades. Gray is very fine, you won't hurt it with that. You need to spin the rims to get an even effect. You could do this on an axle with a fixture but the speed has to be constant. And somewhat low. I'll throw a number out there for grins — 50 RPM. So a tire balancing machine might be too fast (and dangerous). IDK how you're going to mount just that part. Change your pad around often and they wear and load up.

I guess I'd cut a plywood circle and secure the rim with screws that were barely proud of the surface. You might have to change screw locations to get an even sheen right at the bolt circle.

If I had (you had) a big lathe, no problem.