Tangible Sequencer Interfaces - Bubblegum and Ball Bearing Drum Machines
The Bubblegum Sequencer is a physical step sequencer that lets you create drumloops by arranging colored balls on a tangible surface. It generates MIDI events and can be used as an input device to control audio hardware and software. Finally, people can't claim anymore that electronic music isn't handmade.
Also, check out the similar BeatBearing.
The BeatBearing project is a simple Tangible User Interface that uses ball bearings to program a sequencer.