When the pop up card is opened 180° a flat platform (supported by two open boxes) appears to float above the card.
How to Make Pop Up Cards, Tutorial Level of Difficulty: Medium
How to make a rectangular floating tabletop pop up card.
Cut a rectangular tabletop. Mine is 4" wide x 3" high.
Cut your base card. It must be at least twice as wide as your tabletop and at least the same height as your tabletop. Mine is 8.5" x 5.5".
Make two open boxes.
--Start with two long strips of card stock a little more than twice the length of your tabletop and an appropriate width to support the table. Mine are 8.5" x 1".
Unlike in the examples here, unless the boxes edges are part of your design, you will want them to be the same color as your card base so they disappear into the background.
Shown below are the base card and box strips.
--Measure off a short tab at one end of each strip. Divide the remainder of the strip into four equal parts. An 8.5"-long strip works out to: 1/2 inch tab, 2 inches for each box side.
(Why this length? Warning, mathematical digression.... A strip the same length as your card width will form a box 1/4 the width of the card. As the card closes the box collapses from the fold toward the edge of the card. Collapsed, the box is exactly the length of half the card--the distance from fold to edge--meaning it will stick out of the card if it's any bigger! Taking the tab off the end makes it just a tiny bit smaller to make sure it will fit.)
--Score, fold, and glue strips into two square boxes.
--Glue the two boxes together along one side. Pictured below with the tabletop to show that the widths are the same.
Create your floating tabletop.
Your tabletop must be at least as wide as the two boxes glued together, in this case 4". Any narrower, and it won't cover the top of the boxes.
IMPORTANT!! The size of your tabletop piece dictates both the size of your boxes, and the size of the base card! So...when you try this with other shapes, you must start by measuring the tabletop and cutting the box strips and card base to match.
--Score and crease the tabletop in half. The crease will run the same direction as the fold line of the card base.
--Glue the tabletop to the tops of the boxes, aligning the crease with the box join line. You can do this flat, from the top, but I find it easier to collapse the boxes and tabletop and push the fold of the boxes into the fold of the tabletop.
Glue box bottoms to the card.
Align the center fold of the base card with the join line of the boxes. Again, you can do this with the boxes open, but I prefer to flatten the boxes. (You will crease the tabletop the opposite direction as it was when you glued the boxes to it.)
Now for the fun part. Your tabletop need not be rectangular, and it need not be symmetrical. Your mechanism will work best if the sides are balanced. Otherwise it tends to collapse toward the heavier side.
Here's a simple heart.
I should have made the boxes a little smaller: see how the one on the right hand sides shows a bit?
Remember the tea cup valentine? It's a simple tabletop, except when I was done I found the cup was so heavy that the whole thing pulled to the left, which also prevented the steam from rising properly. I had to add a diagonal cross brace in the right hand box to act as a stopper, preventing the smaller box from collapsing as the card was pulled open.
Molly put a roof on it (so clever!) and made a little house. Wouldn't it look cute all done up like a dollhouse?