I redesigned the Hedron deck box from the ground up. This box includes space for 100 double sleeved cards(80mm depth). It has 2 large spaces for dice.

This requires 12-8mmx2mm round magnets. I designed these to push into box without glue. Let me know how well this works for you. It has worked great for me and wasn't hard to insert.

You will need to print 8 panels. I used hot glue to put these on the box. I'm sure superglue would work as well.

Magnet strength- I use these magnets from Bambu. I have tried ones off amazon and its hard to figure out what the strength is going to be these bambu magnets work well for me. https://us.store.bambulab.com/products/round-magnet?id=42424856477832