If you haven’t already, please see the preceding articles on making trading cards at home:
DIY Trading Cards, Part 1
DIY Trading Cards, Part 2: Making it Physical
DIY Trading Cards, Part 3: Specialty Cards

After you have designed and printed several varieties of cards, you may want to distribute them. A nice touch is with a custom package.
I have included the native GIMP file and also saved to Photoshop.
trading_card_pack.xcf (237 KB)
trading_card_pack.psd (634 KB)

The design can be as simple or as elaborate as you want.
Fold the short ends in first, then the two longer ones on top. Use either tape or a sticker of your choice to hold them closed.

Next Up: Card Box