The latest Switch & Lever video takes a look at building a custom MIDI controller, based on the Arduino platform.
Arduino is an open-source electronics platform, based on easy-to-use hardware and software
TheMIDInator is a MIDI controller based on an Arduino MEGA 2560. It uses a few potentiometers, rotary encoders, a joystick, switches and a keypad as inputs and sends MIDI commands via serial USB interface to the computer.
For this controller to work properly a program such as Hairless MIDI to Serial Bridge needs to be running on the computer to receive the commands. This can then be piped into your DAW of choice.
You can download the code and circuit diagram for this project at Github.