[joshu]

From a purely mechanical point of view, writing is fairly hard. You have to do more than bring a pen into a position, you have to apply some pressure, as well.

I'm currently building a whiteboard plotter (as opposed to a pen) and it is a PITA.

[gregpilling]

is there any software out there that does this, or did you write it yourself?

[joshu]

Yes. I am using a CNC motion controller (right now, GRBL) and it processes gcode generated by Inkscape.

Here is a video in which I test a parameter change (too far, in this case - it wobbles): http://youtu.be/a3iNFk0GibE