Replicates old "spirograph" toy. Which has a small gear (circle) within a large circle. Adjust ratio and pen distance from gear center for different patterns.
My previous project tried to simulate actual mechanism of the toy, with pen in hole number 2. This one just uses the spirograph equations for hypotrochoids (spirograph technically produces "hypotrochoids"). Varying ratio and pen distance from gear center has many more possible patterns. Note that smaller ratios make larger patterns. Consider that when gear (smaller circle) is very small with pen distance from gear center of zero, the pattern is close to a circle the size of the larger circle. Note that pen distance from gear center really shouldn't exceed the radius of that gear. Note that pen distance from gear center can't exceed the radius of that gear.
