The electronics used here are pretty standard for 3D printing, an Arduino Mega with a RAMPS shield ... [Jonathan] has made all of his build files, software and firmware available on his page ...

I build robots that move, blink, and sometimes even creep you out. From animatronics to 3D printing experiments, I fuse ...

but 500g is pretty healthy for a 3D printed unit. On the electronics side of things, a bog standard CNC shield hosts A4988 or DRV8825 stepper driver modules and sits atop an Arduino Mega2560.