“A parametric cylinder sinusoidally dented along the Z axis.
Can be used as:
Star exclamation style shape
Gears: helical or straigth.
Very smooth run as long as relatively same nr of teeth
But intolerant to dirts as the teeth nearly fully engage
Planetary gears: helical or straigth.
Threaded shaft + corresponding tube
Dented surface on the inside
Left/Right constant angle twist added
Round surface down to a polygon for torque transmission”