Get the plans to make your own folded card holder on your laser cutter.  It's recomended that you use 3-4oz vegetable tanned leather though you can use a slightly lighter weight leather for the card slots to help reduce the overall size.
 
Additionally you can choose to omit the two exterior card slots to make a 2 card wallet instead of the 4 card wallet that is in the designs.
 
Black - cut lines for each of the card slots and the card holder body.
Red - are the holes for sewing the wallet.  If you are going to hand punch the holes with your leather working tools, set these to ignore.
Green - reference marks for alligning the card lots properly on the card holder body, you likely set these to ignore, or if you feel like you need them, set them to engrave very lightly.