My daughter is very into Pokemon cards right now. It started with Pokemon Go! but has spread into card collecting. We tried playing the card game once and it was SO complicated!
Part of playing the game is having a deck of cards - the higher skill cards beat the lower skill cards, or something like that anyway. Each deck can be 30 or 60 cards but when you have hundreds of cards, you need something to put them in.
Therefore I made her deck boxes for her cards. I started out with one, then two, I think she has about 8 now. She sorts some cards into her binder, some into a "special" mini-binder and some into the deck boxes.
These are printable Pokemon deck boxes. You can edit the name on each box before printing. I used white cardstock then laminated the cardstock with clear Con-tact paper before cutting them out and assembling. It's simple - cut on the solid lines, fold on the dashed lines.