There are times when I'm on YouTube watching a math video that I think, “oh, that would be fun to play with!” What I should do is recreate the diagram in Desmos or Geogebra. But instead I just move on to another video. Recently I decided I should try making some diagrams, in part to improve my Javascript/web skills, but in part because it seemed like it'd be fun! So I did this for two math videos:

Mathologer multiplication on a circle
3Blue1Brown Feynman's Last Lecture

Both of these were quick, under an hour (mostly fiddling with colors, line widths, transparency, etc): an ellipse from line segments, multiplication with modulo on a circle.