Top can hold trading card game deck, bottom has room for tokens and dice. Both top and bottom friction fit - I was surprised how well that worked out without much effort on my part. I used proofgrade cherry plywood. .
First real project and it was a very pleasant learning experience - for example, you can see my finger joints evolve as I did the core, then the bottom, then the top lid.
I may still glue a little engraved medallion into that spot to help you grip the core as you open it - so it still might happen for this version. The circular opening was already suppposed to invoke the inner design of a pokeball, so another option was to engrave the top and bottom of the outer circle onto the lids - but my daughter liked the look of just the pokemon better.