I got a bunch of Tyvek scraps from misprints at work and thought I would do some projects with them. They are all poster sized but i cut them down to what i needed. If you cant find any sheets of Tyvek, lots of mailing envelopes are made of Tyvek and are free. Tyvek is a plastic product with the basic properties of paper. It is water resistant, and nearly tear proof.

Step 1: Cutting and Folding

I got tired of folding up my paychecks and wanted a wallet big enough to hold them. Thats how i decided how large to make this wallet; big enough to fit the huge (not in amount, but sheer size. why are they so big? my checks are one third the size) checks I get.
I started with a piece of Tyvek 4 times the height of the check and a little wider. IT was about 10x14 inches. I folded the sheet in half then each of those in half as well. One fold will later house the cards, one the cash and receipts, and the "hidden compartment " on bottom would hold the checks.

Step 2: Securing the Sides and Adding Cards.

I thought about sewing the sides, the Tyvec would have held up, but I got lazy. Maybe I'll sew the next one. Instead I grabbed some ribbon and super glue made a hinge. I glued half the ribbon to one side of the folded wallet and half to the other side. After gluing the ribbon I created the center fold. None of the folds are very tight, and I wanted them to be that way so it stays loose.

I made the cuts for the cards with about a quarter inch of space between cards. I made a second slot above the first along the same lines.

Step 3: Filling the Wallet

The cash goes in the back slot, after fitting the cards into the card slot I glued the top shut so I could not put stuff in the slot with the cards. The cards were a little loose so I added 2 1/8 inch thick magnets to hold them in place while the wallet is closed.

Step 4: The Final Product

Here is the final product. I added 4 more magnets to keep it shut. It probably would have settled down and gotten flat on its own, but i had a bunch of those awesome little things laying around, and what else was I going to use them for? There are a total of 6 magnets in the wallet. A thicker wallet would hide them better, but since the whole thing is so light the magnets can easily hold it all together.