This toy explores the Petr–Douglas–Neumann theorem. Starting with any N sided polygon, we add a triangle to each side, and generate a new N sided polygon from the tips of those triangles. The triangle has a specific angle at the tip, and we repeat this process with a sequence of angles. After N-2 repetitions, we end up with a regular N sided polygon. For details about the sequence of angles, why this works, and how it's related to the Discreet Fourier Transform (?!?!), check out this Mathologer video.