The wallet uses only three pieces of fabric, the outer piece, and two inner pieces forming the inside of the money pocket and the card pockets. The dimensions I used are these:
8" x 4"
7 3/4" x 3 3/4"
7 1/2" x 3"
I worked out the sizes from laying out 3 credit cards in the arrangement I wanted, with a suitable amount of space in between, and accounting for about 1/8" edging around all sides. The significant idea is that each piece is a quarter inch shorter, lengthwise, than the next biggest. The ends, however, will be sewn matching up, making the outside long and the inside short. Properly controlled, this length differential creates the desire to fold up which is this wallet's most excellent feature.
Sew bias tape to one of the long edges on each of the two smaller pieces.