The pulley at the right can be gradually moved out on the boom such that the cat operating the door is so far away from the food that the other cats will get most of the food.

I made this for several reasons. First I like that the cats are active, doing something that they like. Teaching the cats to operate a lever or switch opens many possibilities for teaching them to do interesting things. Also I am curious as to what happens when the opening mechanism is moved out the boom. Will the cats develop some sort of altruistic behavior taking turns to feed each other?

Zimba the male cat learned in a few days to operate the opening mechanism. The other cats have not learned.