I've been working on a marble dispenser for the little ones. The box in the center is meant to be pushed. When pushed, it aligns three slots and allows the marbles to drop. (See figures). The problem that I'm having is the marbles aren't even making it through the first slot--if two or more try to enter at once, there's not enough room and they get stuck.
I tried using a funnel to feed marbles into the hole, but they still get stuck. Any ideas on how to prevent that?