Strain-wave gears are becoming popular in many areas including astronomy for sky-tracking telescope mounts, they're kind of odd but clever. https://howtomechat

Strain-wave gears are becoming popular in many areas including astronomy for sky-tracking telescope mounts, they're kind of odd but clever. https://howtomechatronics.com/how-it-works/what-is-strain-wave-gear-harmonic-drive-a-perfect-gear-set-for-robotics-applications/ https://howtomechatronics.com/how-it-works/what-is-strain-wa... If you search on YouTube there are a couple of good videos where people have 3D printed their own to demonstrate the principles