A derivative of the classic, and hopefully an improvement. Fishbone gears are known to make less noise and have less "play" as they turn, with no "give" when they begin turning as normal gears do.This was kind of an experiment. I've never held or seen Wade's original extruder in my hand, so hopefully this is an improvement. Give it a try, but be warned that my STL exporting plugin doesn't play nicely with scale. If it's coming out the wrong size for you, look here for reference: (the original!)http://www.thingiverse.com/thing:1794Works just like the original. Instructions here:http://www.thingiverse.com/thing:1794The SKP files are directly from SketchUp.