I needed a card to put some cash in as a Christmas gift so I decided to get in the craft room for the first time in a while.
Here's the diagram I made to help me cut and fold the card.
Cut a piece of paper to 6.75" x 8" and score at 3" and 6" on the long side, cut out a corner from the 2" piece, then round the part that's left.
You'll have something like this:
Then tape it up on the left hand side with a thin layer of adhesive
After it's all decorated you have this: