I built a Polargraph (www.polargraph.co.uk) at HACKBMTH 2013 @ REDWEB and these are the models I designed. One is to mount the stepper motors and the other is a pen mount for a whiteboard marker.This polargraph was made at the HACKBMTH 2013 event. Made from scratch in 9 hours from stepper motors scavenged from an Epson Stylus 600 printer a dual stepper shield from iTead Studios, an Arduino Uno, string and some spanners for counter weights and the 3d printed parts designed and printed on the day. I didn't really know how this was going to turn out as it was built on the fly and adapted as I went. I ended up making use of a white board as the drawing surface, string to suspend the pen and 3d printed parts for the motor mounts, pen holder (gondola) and http://www.thingiverse.com/thing:44888 for the spools. I managed to get it working but ran out of time before I could calibrate it. In the first picture it is half way through drawing a square. The motor mount is very basic and probably only any good for the Epson steppers but the scad file should be pretty easy to alter to suit as it is somewhat parametric. Same with the pen holder. Control software and firmware for the Ardunio available from www.polargraph.co.uk http://hackbmth.org/