For those of us old enough to remember, Spirograph was a drawing kit consisting of transparent gears with holes. You would place a gear inside a larger ring with teeth on the inside, put a pen into one of the holes, and rotate the gear around the ring, which would make the pen draw an interesting repeating pattern. Different holes would create different patterns, as would other gears with larger or smaller diameters.
By using the same idea in the world of Motion, you can recreate the this effect. In this episode, I walk through the process of creating a virtual ring, gear, and pen, and then animating the gear to create these patterns. By employing a particle emitter, a few shape objects, and some parameter behaviors, you can easily recreate these beautiful patterns yourself. And you can take them further than the flat world of pen and paper by expanding the designs in 3D space, as I demonstrate towards the end of the episode.