I sleeved all my Wingspan cards from the Base game, European, Oceanic, and Asia expansions and wanted a single box to store them all in.

It just so happens that the European expansion box fits 3 columns of sleeved cards quite nicely.

Pictured are all bird cards from the Base game, European, Oceanic, and Asia expansions sleeved in Gamegenic matte sleeves. I store the other cards in the base game box.

I've included two halves as well if your print bed isn't big enough. I just used some gorilla glue.