Early test of a 3-servo robot arm for drawing. Rotary joint distortion causes distinctive look. BS2 shown in these initial tests, but ultimately this will be a 20M2 project, accepting input through a PS2 keyboard and printing ASCII characters.
I should strike the comment on isolation profiles... you don't want that for a Pen but you might for a cutter. Both can be handled in Eagle CAD.
Using the CAM processor and HPGL as the device you can set your pen width to get a simple text file to describe the lines to be drawn. I under stand the plotter units (plu) used are 40 plu per millimeter and 1,016 plu in one inch. From a simple test most pads, tracks and text was made from straight lines - simple point to point with pen up or down... there was only the mounting hole that was drawn as a circle - I think that's the hard one.
I had this setup working at Parallax's Expo for National Robotics Week, so I used a Parallax BS2. I didn't dwell on the fact that I used a PicAxe 20M2 up front to read the keyboard and create a macro that auto-typed "Parallax Expo 2012". I'll port it all over into the 20M2 pretty soon.