Cut a piece of duct tape preferably this long for a normal sized wallet
Then cut another just like it.
Lay the second one over the first one. Then cut two more just like those, but don't make them touch each other
Lay then wherever you have room.
Take the piece of the over lapping part of the wallet, the piece that's under the other. Take it and rip of of the tray or cutting board.
Lay the two separate pieces on it.
Fold it. If you think it's too long, feel free to trim it .
I had to trim mine a little.
Repeat step 3, but make sure it's the same size as the wallet.
Then cut two pieces a little shorter than the ones you just cut.
Lay one in the middle at the top.
Lay the other one over the first one, and leave a little sticky at the bottom.
Lay that part over the first part, and... There's your bill fold! And fold it with the wallet to get it used to folding
You can also add credit card pockets, ID card holders (if you have clear duct tape), and whatever you want. I'll post guides on those too!
Hope this helped you!