I used the fusible fleece in my bow tucks. I doubled cardboard, taped it together, then covered it with fabric for the bottom. I've done this in a lot of totes and purses and it works just fine for me. If you're worried about dampness, you could always wrap the cardboard in plastic wrap or something to protect the cardboard. I felt I could replace the bottom very easily, so I didn't do anything for dampness.