DuoGraph: Joe Freedman’s Compact Drawing Machine

The DuoGraph is the follow-up to Joe Freedman’s Cycloid Drawing Machine, and it trades complexity for approachability: seven gears and a handful of adjustable parameters, and it will draw endless geometric figures — Spirograph patterns with a mathematical conscience.

What makes Freedman’s machines more than toys is that they make the maths visible. Change one setting and the whole figure reorganises itself, so the drawing teaches you the curve while you make it.

More: the DuoGraph on Kickstarter · Lissajous patterns.