Copie de Multiplication Wheel:
Multiplication wheel: Equally spaced points around a circle correspond to a number (you can change this number with the first slider). Lines are drawn in to connect each number with one which is a certain amount bigger (the second slider). By varying this, we can see how the pattern evolves with time. Look out for cardioids and nephroids, etc.
For an excellent explanation and some interesting background, see https://youtu.be/qhbuKbxJsk8