The topic says it all. I'm not thinking about sleeves, really, but how do you keep all the cards together in the box? I just keep them in two piles: player cards and encounter cards (including quests). At first I was using the small ziplock bags that come with the core set. But once you buy even one adventure pack, you end up with more cards than will fit in there. I've currently just rubber-banded them together, which seems fine if this were an ordinary deck of playing cards. But I'm interested in preserving these over years, and the rubber band seems like it will eat into the sides of the cards. Anyone have more experience with this than myself?
Thanks for replies!

ventilation. Also, I use the Keep it Dry moisture absorbing packs to keep mold away from my cards. I live in a humid climate. I had have my fair share of mold damage to games I once loved. I change the Keep It Dry pack once every 3 months or so, or when needed.