Involute gears are awesome.
Video made for Summmer of Math exposition 2 - #some2
Sources: https://www.tec-science.com/category/mechanical-power-transmission/involute-gear/
I used Manim for this video, and developed an addon for drawing gears:
https://github.com/GarryBGoode/manim-GearBox
Manim sources for the video:
https://github.com/GarryBGoode/Involute_gear_video_sources