I tried printing the Z toothed pulley rim last night. On larger movements my repstrap performs pretty well (like the outer circle), but on smaller movements there tends to be quite a bit of deformation (like the inner circles). Part of this may be the way the pen is suspended giving it slight free motion, I'm also going to try putting some grease on the worm gears so there is less freedom in the axis when the direction changes.
I've updated my CAD plotting library
I printed this file:
With this result:
Circles, lines and arcs are now supported. Most of the inaccuracies are to to the pen not being well secured.