Fold the flap so that it stays open when the box lid is closed, or use some of the cut-out cardboard to create legs to prop the flap open. Cover the inside of the flap with aluminum foil.

You also have the option of renting plastic crates instead of using the standard cardboard boxes. While they're not necessarily ... closed You might be tempted to only tape one end of the box and fold ...

In this activity you will need to cut up a cardboard box and other materials, so please supervise your child and help them out when they're using scissors. Angle your new longer flaps to face each ...