After a trial basis to find measurements, this is what I came up with -
Started with a piece of card stock 5.25" by 3.5 inches. Scored it at 1.75" down the middle, and .75" from each end.
Next folded the score marks and made cuts so it would be easy to fold and adhere. Used my circle punch to make the half circle in the middle.
This is what my little project looked like after making 8 card holders and making the outside of the booklet. Not sure if you can tell but I put the Michael's gift card first in the stack.