by enhydra, published
This is #35 from "Five Hundred and Seven Mechanical Movements" by Henry T. Brown.
Creating proper elliptic gears is quite sophisticated. I did something like a workaround: I created two gears, sliced and merged them into one. It works fine, but I would not build it into a real gearbox because of the poor efficiency.
You will need a screw M6 by 10mm for fixing the small Gear.
If you scale down
- to 66%: a M4 by 6mm should work
- to 50%: a M3 by 5mm.
And finally you need a rubber band for the Wedge and Base.
Preview in SketchFab: