Hello, and welcome to this instructable on how to build a custom, cheap and easy USB MIDI controller, based on Arduino. The best news: no hassle with USB-to-MIDI interfaces, or software tools like Hairless MIDI, just plug 'n' play!I included readable, basic code for both the Arduino Uno (or Mega) and the Leonardo (or Micro), and I created a MIDI controller library, for those not so comfortable with the programming language, or for those who just want a quick controller without having to writ...