One major variation is using a 2L juice carton instead of a milk carton. Check out my other instructable
for some direction on how to do this.
This Instructable shows how to make a wallet with pockets accessed from the inside seam of the wallet, however depending on how you like to use a wallet, you may want a coin section or outside accessed pockets.
For outside accessed pockets, all steps are similar, only the template cutting differs. Pictures one to three show the template for outside accessed pockets. Folding process remains the same.
If you want to add a section to hold coins, follow the process to make inside accessed pockets and crease diagonals to allow the pocket to be squeezed together to insert coins. When the wallet is closed all of the coins will be shut in the wallet and will not escape into your pocket. [see pictures four to six]
Enjoy experimenting and try other Tetrapak packaging. The 1L pacakge is good to hold typically sized notes, however other packs may be useful for other wallet purposes.