Homebrew PCBs

Hello all,

We've visited this before - the Silhouette cameo vinyl cutter that 
Mike used to directly cut traces in copperclad. Unfortunately, I was 
not able to get his technique to work very well, but now I'd like to 
use the machine to "print" traces using heat cured electrically 
conductive one-part epoxy. What I'd like to do is convert the cutter 
to a plotter. As it is now, the vinyl cutter uses its proprietary 
software to cut (or sketch, using a pen holder) around the edges of 
the traces, which is fine (sort of) for isolating the traces, but not 
what I want here. What I'd really like is to use it like a plotter, 
drawing the traces down the middle of the designed trace. The width 
of the trace could be controlled by using different needles on the 
dispenser or controlling the air pressure.

I'm willing to rip out the electronics and make my own stepper 
drivers, but I'd like to know what software I would use to run the 
converted machine, presumably using some form of HPGL. Does anyone 
know how this would be done? I really don't want to reinvent the 
wheel here, but I'm willing to do a bit of soldering if someone could 
point me in a reasonable direction. Thanks for any help or insight!

Mark