The feedback from the Etsy forums about my wallets so far is that people would like more card slots. I had an idea to create little window pockets for different card groups. Then you could grab a group of them when you need them. Modularized.The categories in my own wallet would be: frequently used, health, club cards, library cards, and certificates. That's 5 categories. My cards total one inch in thickness (2.4 cm). My current challenge to solve is how to sew the vinyl so as to make a dimensional pocket. Right now its looking a bit messy with the darts method. Perhaps the zipper foot. My walking foot doesn't fit onto the old Singer machine.