Martin Molin spent 14 months building a huge wooden machine that uses 2,000 marbles to play music. A conveyor belt grabs them at the bottom, and brings them to the top. Then it drops them on different things, likes xylophone keys . . . bass guitar strings . . . and drums. And you have to keep turning a crank on the side to make it go. Watch the Wintergaten Marble Machine make music.
(you tube)
(wise brothers media)