An Epitrochoid is another example of a figure that can be created in Blender using the Animation Nodes addon and a bit of math. Frederik Steinmetz shows how to save a lot of node-wrangling by placing the formulas right inside an expression node.
Everyone who has played with a Spirograph as a kid (and maybe as an adult as well) remembers the variety of geometric forms one can draw with it. Using the Animation Nodes addon in Blender 2.8, a setup can be created that allows to draw all those forms and beyond.