These homemade tumblers have my interest. Right now, I'm using a frankford vibrating tumbler with walnut media. It's cheap and works well for straight-walled brass. However, I just recently swapped out my circa 1976 garage door opener with a new one. The old headunit still works and is just begging to be turned into a rotary tumbler. It's already slow like a tumbler needs and maybe I could re-use an old bicycle sprocket to slow it down a bit more.