Pocket Mechanism - Trammel of Archimedes
Made by Snorvarg, uploaded
The thing works. :) Only problem was the axis-elements: The vertical axis is pretty thin and I broke one when cracking it loose from the print. I recommend printing a raft layer and leave a gap of 0.2 mm between it and the print, at least for PLA as it tends to fuse nearby elements at the first layer because of the heat bed. Guess you can lower the bed temperature as well.
The main part (dark green here) is a big stubborn piece of plastic, while the small handle and the three rotating axes seem fragile.
Luke could increase the size of the axes, and somehow try to decrease the plastic-eating main part, and this model would be a fiver. :)
0.2mm layer height, 0.4mm nozzle