A Spirograph for Resolume and Resolve: a toothed ring, a wheel rolling round in mesh with it, and a pen in one of the wheel's holes. Nothing evaluates a curve. The ratio is two whole numbers because gears mesh, so 96 and 32 close in a single turn with three lobes, while 96 and 31 take thirty-one turns and lay down ninety-six. Ink is subtractive, so two pens crossing go darker, the way they do on paper.
This demo runs the plugin's shaders and a port of its gear train in your browser, so it needs JavaScript and WebGL2. The plugin itself, its source and its downloads are on its repository.