I had a few scraps of 3/4" pine and 1/4" birch plywood. I cut box walls as 2 concentric rectangles from the pine and glued on the plywood. After sanding it made a pretty nice box about the size of a deck of cards (or a pack of cigarette). But all the box builds I've seen seem to cut the box walls from 2 different pieces of wood. Is this only because of the saw kerf? This small box seems to have a good fit, and I can make it tighter by reversing the top (slight differences in the cut line make it snug).
Any thoughts why you'd use 2 pieces rather than one to make the top and bottom walls?