Input: pink gear of tooth number Zp = 20.
The pink gear engages with grey and green gears.
Tooth number of the grey gear Zg = 20.
Tooth number of the green gear Ze = 21.
Grey cam is fixed to the grey gear.
Green cam is fixed to the green gear.
There is a relative rotation between the cams (very slow, 1/20 rev. in 1 rev. of the input).
Different relative positions of the cams make the blue follower strokes change after every input revolution. The video shows how the follower stroke is increased.
The spring to maintain the contact between orange roller and the cams is not shown.
It is said that the mechanism is used in machine making paper pipes with Zg = 104, Ze = 105.