My kids love Wrigley's gum...I love the little plastic containers that they come in. They are so handy once the gum is finished....
Remove the paper after the gum is gone, and you can fill them with flashcards, playing cards, Pokemon cards, Baseball Cards whatever. (And yes, it would take at least two of these to hold an UNO deck, but you get the idea).
Unfortunately, they don't quite fit index cards, but these are great for everything else. They stack really nicely too, and hold up well if thrown in a purse or totebag (unlike the packages the cards originally came in).
Your cards may smell like peppermint afterwards if you don't wash them very well, but the kids I tutor now consider this a perk, not a problem. They love the minty smelling game cards I have.
(This post is not sponsored by Wrigleys or Uno. All opinions are my own).