I use egg crate mattress matts and cut them the shape of the bottom of the box. Then I get a pillow case protector and then put a pillow case on it. This is super easy to clean up I flip it the first time - because the bottom side is clean and then the next time I just change the pillow case. It fits snug in the box so nobody can get caught in between the pad and the wall, you know like you would make sure that a mattress is snug in a babies crib. It works well for me so I thought I'd share.
