Cheap waterproof fly box

Wal-Mart sells these watertite food containers for $3. They are 6.5x9x3.5". A couple of them fit in the 97c mini-crate they sell, I use one for gear and one for flies in my yak. The foam I got from Lowe's. It's roofing and siding underlayment foam. It's not too strong, but very cheap and is actually the perfect width for the box! No need to cut slots, as the foam is soft. A little quick grab craft cement will stick it well. The center section is just two pieces glued together.