This is an origami wallet. It's small, sleek and simple AND you can write on it(because it's made of paper). However, it's not very practical for use with actual money; I suggest using it for transportation, business, gift, or any other kind of card. To make one, you need a piece of 9x9 paper and about 2 minutes.
Step 1: Paper Preparation.
If you already have a piece of 9x9 inch paper, then you can skip this. If not, get a regular piece of rectangular paper (preferably rather heavy paper, for durability), fold over the edge(but try not to crease it much) to form a perfect triangle, and trim off the excess(and don't you dare let that extra bit of paper go to waste. Nah-ah! Find a way to use it), leaving a folded over square. Unfold.
Step 2: Folding.
Now that you have ze paper, perform the obvious first step of origami, and 1. fold it in half. (Mind you, its hard to use words, so you might as well use the images to see more clearly.) 2. Crease, then unfold. 3. Now take the outside edges and fold them in to meet the middle crease. 4. Unfold and then fold in all four of the outer corners, making the edges sort of rounded-looking. 5. Then re-fold the creases made in step 3. 6. Now fold the entire thing in half, to make something that resembles a square. 7. Unfold, flip over, and fold the edges inwards to meet the last crease. 8. Then fold that in half.
Step 3: Voilà!
And there you have it! Slim, simple, and comfortably pocketable for easy availability, the impossibly simple origami wallet!(Yup, I'm the weirdo posing with a piece of paper...)