I am feeling guilty at the amount of waste from ds2's daily jogurt/quark/pudding pots for Kindergarten snack. I'd like to give him a reusable container, but it really has to be both leak proof and easy to open, as he's only 3.5yo. It also has to be small - think child-sized jogurt rather than the usual size. Any recommendations? I've seen some of the bento ones but they are all stainless steel, and I can't imagine that that's nice to eat out of with a metal spoon.