I was looking for a CVT for my next project when this came up:    About a year ago an Italian start-up got a patent for a gear based CVT transmission module (however there seem to be earlier implementations of ta very similar system). The video above illustrates its inner workings in detail. Obviously, I could not resist and had to recreate it. But as I'm spending summer far away from my Lego, all I could produce is the digital model, which you can download here -> ht