The Gadget Master in question is one Ivan Roulson.
Liz Upton writes:
Ivan took that sad glockenspiel home and gave it a Pi for brains. He designed and built some hammers, and hooked up a motor mechanism and some rubber bands to make the hammers snap back up once they'd made contact. Ivan then proceeded to make the whole apparatus dingle-dongle its way through some sweet, sweet music using Python.
You can read the full details on the rPi Kitchen website ("Cooking up some circuits with the Raspberry Pi"), where Ivan writes:
Programming this in Python is relatively straightforward – just allocate most of the GPIO outputs to controlling the motors and then trigger them sequentially. The motors are connected to the GPIO outputs using a pair of ULN2803 darlington driver ICs. It’s quick but as we'll see, not the best solution.
I haven’t yet found out how to make the software do a clean exit when CTRL-C is pressed – something to do with creating an exception and then using this to shut down the GPIO outputs. Without this, it’s possible to exit while the motors are energised meaning that the peak stall current is passed through the darlington drivers. I’ve had to replace a couple already.
So, Ladies and Gentleman, we present Beethoven's Ode to Joy (among others). Take it away, Maestro Pi!