I stopped my local Staples today, and they had these tins for putting gift cards in if you give them as gifts. They had one that was maybe a little more than 3" square, and about as thick as an Altoids tin, that had a single piece bottom. They had a second that was a little longer, that had a press fitted bottom. Either was about two bucks.

I'm thinking I might have to pick one of the square ones up.