Arduino is a open-source single-board microcontroller. It can be used to interface sensors, rotors, knobs, buttons that will interact with coded applications. You can build specific devices with it. It's an interesting tool to create interactive objects in real life.
I built this device as a prototype :
2 knobs, 3 buttons, IR sensor to send CC midi messages to Ableton Live Made with Arduino.
Original Music : Modeselektor - Sucker Pin
Controlling a servomotor with a knob via Arduino
"Beam control" on a filter...