rock tumbler Answered

There is
Try my rock tumbler.
https://www.instructables.com/id/Hobby-or-Case-Tumbler/
I built this one for polishing brass bullet casings for reloading but it also makes a good rock tumbler with the right polishing media.
Joe

I'm making a lego NXT one, with adjustable speed and all that. Posting in maybe a week. Gotta test it first.

You may want more than a week though. It takes quite a while to polish rocks.

yay. hoorah for rock lovers. i like your "can do" aditude

I'm making one, I'll then post the instructable. It will actually be a 'ball mill' used for grinding chemicals as well.