It came around time for my sister-in-law’s birthday, and rather than getting her gift cards this year, we decided to go with the gift card accepted everywhere: also known as cash. I whipped up a French Bulldog by modifying a dollar origami (standard) bulldog model by @JanessaMunt to give it the right ears. Needing a second model for a second bill, I decided to go with BB-8. My original design used a $50, which gave it a nice coloring but required folding a small strip along one of the long sides to center the black circular mark (on the front of the bill) in the center before following the steps down below. I did diagrams for a more affordable version. Luckily the back of the $1 bill has a huge nicely centered circle on it.
The affordable version:

Diagrams:

The antannae take a little adjusting to get right. Don’t be afraid to let the back get a little messy while you massage them into place.
The expensive original:
