Yeah, the process seems to roughly be: 1. Mount special pen to RepRap 2. Plot traces on PCB multiple times 3. Correct errors by hand with pen and scalpel

Yeah, the process seems to roughly be: 1. Mount special pen to RepRap 2. Plot traces on PCB multiple times 3. Correct errors by hand with pen and scalpel 4. Immerse in chemical solution that dissolves copper around traces 5. Remove pen ink with acetone 6. Drill holes with drill press 7. Apply solder on top of all traces 8. Solder in components Step 2 is the only automated part. Considering all the CAD work you also have to do, it seems like it would be easier to just draw the traces by hand in the first place. I helped a friend build a Mendel and I can tell you that it is a TON of work, inevitably requiring much ingenuity and overhead expense. I'm still very excited about the potential of the whole thing though.