Anyone have any ideas on a homemade brass tumbler or vibrator? I like making my own stuff when I can and this seems like a fun one to try.

You could buy several for the cost of making one ..... cheapest is to buy a cheap 110 VAC cement mixer ...

sure.. lots of ways to do it.. and a belt drive, with a 3# coffee can (pulley on the bottom) connected to a 900 rpm (and then geared down) works fine.

30 bucks from midway, though..

I've made one.

The drum of the tumbler itself was made from 6" dia PVC tube with a couple of screw on end caps glued into place on the ends.
3 lengths 1" dia pvc conduit are also glued to the inside of the 6" tube to increase the stirring action.
The tumbler/tube assembly is then supported on two horizontal rollers, one of which is driven via a belt from a sewing machine motor.
The two rollers are supported in a simple fabricated tubular steel frame.

The design is similar the the Thumlers Tumbler with the horizontal drum which will explain it better than I can describe it with words.

I 1/4" fill the drum with walnut media, dump my brass in, screw the end cap on and then set it going at about 50rpm.
I control the speed with a triac controller.

It works very well but probably isn't as fast as a vibratory type cleaner.