Take your 9 x 13 fabric and measure down four inches, then another four inches, then another two inches. Mark these measurements with your marker on both sides of your fabric to ensure that your measurements are accurate.
At the ten-inch mark, cut your fabric so that you have one 9 x 10 strip and one 9 x 3 strip. Cut the 9 x 3 strip in half so that you have two 9 x 1 ½ strips. These strips will become our pockets.
Going back to your larger 9 x 10 inch piece, you want to fold the fabric over at the 4 inch mark. You should form a kind of pocket, with a 2 inch flap still hanging over. Fold firmly so that it stays!
Fold the 2 inch flap over on top of your pocket. Place a library card or other card within this 2 inch flap to make sure that you can still get to the card when it's in this pocket!
Place one of your 9 x 1 1/2 strips on the surface of the wallet, underneath the 2 inch flap, and underneath the card you've placed there for measurement. You want the strip to rise slightly above the top of the card. This is the start of your additional pockets.
Measure out a 9 inch strip of duct tape and rip it in half lengthwise (hot dog style). Use this strip to secure your 9 x 1 1/2 strip to the surface of the wallet, creating another pocket. Half of this strip should be on the 9 x 1 1/2 strip, half should be on the surface of the wallet.
To add a third card, simply repeat this process. Place your card in your new pocket to ensure that you can still see the top of it, then place your last 9 x 1 1/2 strip behind it.
Tape it down with your remaining half-width strip that you tore off in the previous step. Your wallet now has three long pockets!
Make sure the the pockets are laying flat. Then tear off a half-strip of tape and tape down both sides of the wallet. Make sure that your strip is half on the front side, with half hanging off...
... Then flip the wallet over and fold over the strip onto the back side.
Trim off any excess tape from the bottoms of your side strips. To open up the money pocket of your wallet, carefully trim away a tiny strip across the top of your wallet. You want to cut off the fold so that the two layers of duct tape fabric are opened up underneath.
Finally, your wallet's pockets are awfully long! You're going to want to divide them in half with another strip of duct tape. Tear off a tiny strip of duct tape (about ¼ inch). Fold your wallet in half in order to find the center.
Then, place your strip of duct tape down the center, perfectly dividing the wallet's pockets! Fold the remaining end of the strip over into the money pocket.
Your wallet is now ready to carry your money, cards, I.D. -- anything you may need!