Hold two cards together like you see in this image. Use the numbers on the corners as a guide to help center them. You want both ends that stick out to be as equal in length as possible.

Fold both ends down as you see in this image. Try to get the folds to align with the edge of the card as best you can and make sure the folds are squared.

Turn it over and do the same thing to the other ends that stick out. Remember to keep it as centered as possible.

Now we're going to lock the two cards together to form a sort of tile. Tuck one end of the cards together as you see in this image.

Then tuck the flap on the other end on the other side. You end up with two cards locked together.

Since a box has 6 sides you'll need to make 6 tiles.

Now we're going to attach the tiles together to form a box. We'll be using playing cards to form a hinge. Stick a playing card between the two cards of one of the tiles about half way.

Then fold the card in half. You've just made your first hinge.

First we'll put the four walls of the box together. So put another hinge card on the opposite end of your first tile as you see in this image.

Then slide tiles onto the hinges. Repeat this until you have all four sides of the box hinged together.

Here's what it'll look like when all four sides are hinged together. Next we'll put a bottom on the box.

Take another tile and put four hinges on it as you see in this image.

Then slide the four walls onto the four hinges. The easiest way is to start one hinge. Then align the sides into the grooves. Then work the final hinge in place.

Here's the final box minus the lid. This can be used as a small storage box or pencil holder. Next well put a lid on the box.

Simply hinge the final tile onto the top of the box.

You can also make the box stay closed by adding another hinge/tongue. Push the card in all the way so only about an inch sticks out.

Then tuck it in. The box will now stay closed.

Put a little pencil mark on the top edge so you'll be able to find where to open the box. Trust me. You'll have a hard time finding it.