First step, obviously, is to have a worn out pair of boots. This style of wallet can be made with a 2.75" wide strap of leather, but where's the fun in that?
Next, you have to disassemble the boot. This is not as difficult as it may sound. A seam ripper and a good pair of leather shears or razor knife can have the job done in a couple of minutes. Start at the top of the shaft (the tall part that goes round the leg) and cut the seam that runs down the sides to the upper (the foot part) of the boot. There will usually be a piece of bead in there (rounded off part that is sewn into the middle of the seam), that can just be cut off and discarded. Then cut the seam along the upper of the boot where it connects to the shaft. If you have done this right, you will now have two largish pieces of leather that were once the front and the back of the shaft of the boot.
Take one of these pieces and cut it in half down the middle lengthwise. This should give you two long strips that are about 2.5" to 3" wide, depending on the size of the boot that you have cut up. This will be the body of your wallet. Trim the bottom (the side toward the foot of the boot) square with the sides of the piece. Use a credit card as a guide to see how deep the pouch of the wallet will need to be.. Then fold the leather over to create where the pouch will be. There should also be a piece at the top that can be used a flap to close the top Of The wallet.
Once you have the wallet body ready to go, punch holes for stitching along both sides, as well as holes for a snap. Remember to set the snap before you saddle stitch the sides up. Once it is stitched, snap the snap closed, and you're done! A nifty wallet from a boot! Who'da thunk?