Watch the video: http://pbskids.org/designsquad/build/floating-box-pop-card/
Step 1: Here’s what you need to make your own “Floating Box” pop-up card!
General art supplies for decorating and writing messages
Step 2: Cut two slits
On the crease side of the paper, make two straight, inch-long cuts.
Step 4: Make the box
Once the box is in the card, close the card and press the box flat.
Open the card and check that the box pops up.
Step 6: Add a cover and message
Add a message and decorate your card.