https://www.schmalzhaus.com/BigEasyDriver/

Big Easy Driver Stepper Motor Driver V1.2 .
An Open Source Hardware Stepper Motor Driver .

Based on the Allegro A4983 or A4988 stepper driver chip.
Can drive up to about 2A per phase of a bi-polar stepper motor. It defaults to 16 step microstepping mode. (So if your motor is 200 full steps per revolution, you would get 3200 steps/rev using the Big Easy Driver.) It is a chopper microstepping driver based on the Allegro A4988 driver chip. For the complete specs of the design, read the A4988 datasheet. It has a variable max current from about 0mA/phase to 2A/phase, although I have tested it to 2.2A/phase with a heatsink and/or fan. It can take a maximum motor drive voltage of around 35V, and includes on-board 5V/3.3V regulation, so only one supply is necessary.

Actual pictures uploaded .