Great ! Thank you. I just print the v0.18 and, as discussed on your blog, I wrote some Gcode interpreter that I will share tomorrow.
I was thinking about how to add the z axis and why are you lifting the pen with gears for a translation ? I am wondering if sticking the pen directly to the servo can do the trick :)
Also share a scad version of the gears should be helpfull : my servo can't fit inside both bears so I had to drill them...
Corona : I use cheap no name 9g servo and it works fine !