[Mr. Kim] and [John Sarik] made a presentation(pdf) at last weekend’s Botacon conference on how they made organic field-effect transistors (OFETs). A wooden RepRap, the fancifully named Unicorn from Makerbot (or printed from Thingiverse), hacked felt pen, a handful of chemicals, and a couple of pieces of lab equipment were needed to print (plot) out transistors. We were unable to attend the conference, so this is what we inferred from the slides. Silver ink is printed onto a glass slide to form the gate regions, cured and partially masked-off. A layer of CP1 Resin is spin-coated onto the slide to form the dielectric barrier between the gate and the semiconductor, the drain, and source regions. Silver ink is once again used, this time to print out the drain and source regions. The last thing printed is P3HT dissolved in toluene to form the semiconductor region. It would be interesting to see this process modified so that all coatings and curing can be done without removing the slide from the printer.