It's probably easier to do this with a regular CNC router than with a 3D printer. It's easy enough to put a pen in the spindle and draw; there's no requirement for filament to be flowing, and you can get the machine to lift the pen when needed for the image. Use the engraving function of a CAM program to generate the G-code; the only think you'll need to edit out are the M3/M5 codes that control the spindle on/off. Depending on the router, you'll be able to produce a much larger drawing than with a normal printer, which tends to be rather small.

Andrew Werby
www.computersculpture.com