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!
Paper (8.5 inch by 11 inch copier paper or construction paper)
General art supplies for decorating and writing messages
Step 2: Cut Two Slits
Fold the paper in half.
On the crease side of the paper, make two straight, inch-long cuts.
Step 3: Define the Tab
Bend the tab up and over, and fold it flat.
Step 4: Make the Box
Push the tab into the card. This turns it into a box that sticks into the card.
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 5: Add a Character
Glue a drawing or photo onto the box.
Step 6: Add a Cover and Message
Glue on a cover to hide the cut you made.
Add a message and decorate your card.
Step 7: Did You Know?
Paper bends along lines of weakness. A crease is a line of weakness. Paper typically bends where there’s a fold. Pop-up cards take advantage of this feature by using creases to make the paper bend or move in predictable ways when you move the pop-up.
Step 8: Try This Next!
Make a fancier design.
Use two or more boxes. Or make several boxes that are different lengths and widths. This lets your characters pop up in different places, like near the front and near the back of the card.