I bumped into this interesting question while looking for a fun mechanical black-box puzzle:
Pulling the rope with one hand is as heavy as with two hands?
I wonder if it is possible to generalize this puzzle somehow, say, needing to exert 10N of force with each hand to single-hand pull the inside object up (just translating upward without rotating), but if using both-hand pull, then the force on each hand would be higher (say, 20N) or something.