Rather than write a bunch of stepper motor code himself, he installed and ran a four-axis fork of grbl on the Arduino, turning it into a stepper motor controller.

There are four poles to each of these coils, and they plug right into a standard stepper driver, so to control this board all you need is a basic Arduino and a motor shield.

Arduino has been used to control a stepper motor driver a MIDI interface, scanner parts and basic keyboard to great effect, check out the video below to learn more. Watch this video on YouTube.