Inspired by the MPSCARA, I challenged myself to build my own functional SCARA arm, but with even fewer printed parts. For example, all linear bearings are printed (built directly into the structure for the carriage). The only parts you're really gonna need to go out and buy are the linear rails, leadscrew, steppers + belts, and some M3 fasteners! Everything is controlled by a cheap, off-the-shelf 3D printer mainboard (in my case the MKS Gen L v1 or v2).
More important, perhaps, than the hardware is the software which drives the robot. I've been developing a browser-based software suite which can drive the SCARA arm, generating inverse-kinematic control code on the fly! I learned quickly upon building my arm that there is no robust firmware support on Marlin for SCARA arms (despite some confusing documentation suggesting otherwise). Thus I built my own!
Here I demonstrate the writing capabilities of the jSCARA arm + software, and the precision with which the arm can write. Note that when the drawing gcode is run for a second time, the arm traces over the exact same path!