Link: https://spirograph-curves.netlify.app
In this spirograph-like simulation we start with a fixed circle in the middle. Then we add another circle which moves around its boundary. We repeat this process any number of times. This leads to a number of complex curves.
The interface lets you adjust speed and radius of each circle. You can also choose from a selection of interesting presets.
The app is made with Svelte in order to simplify the interactivity. The drawing is done via SVGs.