How to store cards when game boxes don't have slots for them
Hair Bands



Similar to using rubber bands, but they don't deteriorate and stick to the cards over time. If possible get metal free ones, rather than the type on the right - less likely to catch on the cards.

Small Cardboard Boxes



Have a look around your house, you'll probably find something that's the right size. Plasters often come in boxes that are a good fit for cards.