My Dad made one once by attaching a small electric motor to a board, making a stand for it, attaching a bar with a weight on one end to the rotor below the board (so it was off balance) and then bolting a plastic bowl to the board. The off-balance weight made the motor vibrate and it shook the bowl, agitating the media inside. It was about the same size as a Midway tumbler, and lasted longer than my Dad did, unfortunately.
