This hack turns the Pi into a musical maestro on the glockenspiel.
The Pi-powered musician was created by hooking up a Raspberry Pi to a buffer board that is attached to a glockenspiel controlled by a solenoid - a coil of wire that acts as an electromagnet. The Pi controls the flow of electricity to the solenoid so the bars of the glockenspiel are struck in time to a tune.
You can see a video of the device playing a rendition of Do-Re-Mi from the musical The Sound of Music.
Screenshot: Mike Cook/Vimeo