Actually I think I have it figured out. The main driver is a rolling pin. There is a large black rubber band looking pulley that goes from the motor to the rolling pin. The rolling pin is drilled with a series of holes going around it in three spots. There are little rods stuck in the holes. The rods can be placed in different holes thus making different beats. The rods hit on the three hammers which are sort of loosely held in place by black straps. Those hit on the lid, tin can, and margarine tub.
Very cool too, but $930 US is a little too high for me. I am surprised no one put this into production yet. The price would dramtically drop. Regardless, with the talent here at the Nation, it is buildable. Thanks for sharing. Enjoy.