Hey watzmann,
Sorry i don't have any hints for you; but i'm working
on a similar project called CNC Milling Machine...instead
of a pencil, there's going to be a drill bit which will mill
shapes....lines are easy...but how will you draw arbitary shapes
like curves/arcs? i mean the software part....we have 2 turntables
one moving a x direction, the other in y while the bit remains stationary.
In your case..Is your pencil movable or is the base moving?
Whichever of the 2, how are you going to realise curves in terms of
the movement?
Plizz ur help
Thanks!