Two left hands and no passion nor time for learning piano or guitar? Try out this super simple Arduino Midi-Theremin! This simple Midi Theremin uses a HC-SR04 Ultrasonic Sensor (which is extremly cheap ~2-4€) and produces a MIDI-out signal, analog to the measured distance from an object. Apart from the Senor you only need an Arduino (in this case an Arduino Nano), some wire and some MIDI playing device.
Find the – still alpha – sourcecode here