A hinged dice box that uses disk magnets (6x3mm) as a catch,

Modeled in FreeCAD, Text added in OrcaSlicer

The model can be edited in FreeCAD since DnD dice can vary in size.

A cylinder (pin) with a diameter of 2.2 mm is suggested as a hinged. This can be fixed in place with cyanoacrylate glue (super glue). A 2.1 mm pin is provided as that is what I had printed and used.

The model is shown with the lid and base joint using 0.01 mm of material. This disappears on slicing. It allowed me to model the dice cutouts and hinges in a single "sketch" for both parts using FreeCAD.

Version "r1" was printed and is shown in the images.
Version "r2" is has a slightly hinge wall and larger corner/cove radii. This has not been printed since "r1" is working.

Inspired by:
https://www.printables.com/model/433123-dice-dnd-case
https://www.thingiverse.com/thing:3495922