I was going to say the same as the poster above me. Origami boxes - no cutting involved, and all sorts of paper is suitable. Old 12x12 paper that you're not going to use, for example, old calendars with large pictures, old maps... Any square paper that comes into this house, DH says *Oh, that would make a great box*. Lynn did a fancied-up one as a TLC challenge a while back, but you'll find the instructions for the origami part in this post -
Forums at Splitcoaststampers. And the lid is, as the poster above said, just a fraction smaller. I have a lot of these in my craft room - I keep some unmounted sets in them, leaves, in one and so on. My experience on summer/Easter camps is that kids love folding to create things. And if you want, you can use plain paper and stamp to decorate, or decorate with punched/diecut flowers and leaves.