Sometimes the simple things are the best:
The PrimoGraf is a hand cranked drawing machine. Using wooden gears with prime number based gears an infinite array of drawings can be made. It comes complete with 7 gears, 2 set of rods and penholders so you can create many variations. Different setups can be achieved instantly by simply picking different holes.
Made of walnut, basswood, and solid brass and hand crafted in Portland, Oregon.