I have 3 credit/debit cards, a license and medical card in mine.  So this holds about 4-6 “cards”, depending on the combined thickness.  Please alter the model as needed to hold the # of cards you want and if you need it tighter or looser (more loose? whatever)

I used the fuzzy perimeter to give a good feel and texture, but print smooth if you like.

The two models are very similar, but one is tighter than the other, which may or may not be what you want.