You start with a 4 x 4cm Brick, which you program over USB, but it won't do anything until you add accessories in the form of Bricklets: switches, joysticks, motors, accelerometers and LCDs.

grbl is stepper motor controller firmware for three-axis cnc machines, intended to run on Arduinos with a motor driver add-on board. Engineer in Wonderland cnc-related blogs are indexed here It is the ...