Here is my organiser for the Zenith boardgame. I used a spacer to fill up the empty space in the box AND 4 spacers that go on tope of the player aids to fill the gap between the organiser and the lid. If you only store the box horizontally, you don't need to print these 4 corner spacers.

I printed at 0.24mm layer height and switched to 124% speed once the print was going and it printed fine. There is room for some more cards (for the expansion) but  i don't think it will hold sleeved cards, did not test that