To let your inside out, you will need:
Magazines, photos, and other collaging materials (like junk mail, newspapers, wrapping paper, cereal boxes, etc.)
Glue stick or Mod Podge
A small box that can be unfolded into a flat piece of cardboard — any size, shape, or color will do. Tea boxes and those boxes that cupcake liners come in work great.
If you have the kind of box that opens on the top and bottom but doesn’t unfold in the middle, it’s okay to cut one side of the box to get it to lay flat. After you’re finished collaging the inside, you can just tape it back together.