This is a great idea for when the box that holds your favorite deck of cards has worn out. Use a travel soap dish to hold them. A soap dish is light weight and does a great job of protecting your cards.
You can even take it one step further by carefully cutting a small notch in the bottom half of the soap dish. You now have a portable card tray for playing games like gin rummy while in the car or on the train. The box keeps the cards from sliding around on your playing surface , and the notch makes it easier to remove cards from the stock pile.
If you have any ideas or suggestions on how to improve this idea more, please share them in the comments.