This thread has an attachment for a matchbox card box...post #13 has a .pdf file with directions to make the box to hold A2 cards and envys, just not sure how many... But it's a start!
Forums at Splitcoaststampers
The attached file is for a card purse that can be easily modified to fit the number of cards you want to insert. I got it out of the gallery some time ago, but credit goes to StamperNan...It's cute and looks easy!
HTH!