A 3D print version of the AxiDraw. Which is a pretty neat CNC, but costs $450 if you buy the kit from evil scientist. This route…Oh and the author lists out all the parts…maybe $150 when done.
http://www.thingiverse.com/thing:1517211
Oh here is another one on instructables http://www.instructables.com/id/4xiDraw/ which you can get the files here https://www.youmagine.com/designs/4xidraw