This is a fun little MIDI interface based on an Arduino. It converts the x/y movement into a MIDI signal. There is a promise of more details soon. In the mean time, check out this tutorial about creating MIDI output signals from an Arduino.
This is a gesture controlled MIDI controller I designed and built. It has a tilt sensor which affects to MIDI parameters it is sending out but also the color of the ball. I built several stereotypes to get it work the way I preffered. The pictures are from third generation. I am currently putting together fourth generation with better LEDs.
In the Maker Shed: Arduino Mini Board, fully assembled