Spotted in the MAKE Flickr pool, this homemade jewelry tumbler from user Copper Pete, who built a custom plywood case and packed it with repurposed parts from a dead printer to create what appears to be a pretty nice little machine. I think the drum, itself, is a purpose-made component.
I’m thinking a 3″ or 4″ section of PVC pipe with a cap on one end and a screw-in cleanout fitting on the other would work well.