For an easy plotter design that you can build with only simple hand tools, be sure to check out this tiny project from Mr Innovative. The machine features a pair of stepper and lead screw assemblies to maneuver a pen in an X/Y plane, along with a clever string and servo setup to handle retraction.

An Arduino Nano and two L293D ICs mounted to a custom PCB are used to control the device, though a breadboard could certainly substitute for the PCB in a pinch. Drawings are translated into the proper format via Inkscape and Processing. 

More details on the miniature machine, including code, can be found in Mr Innovative’s write-up.