The case is a print-in-place model which should be quite easy to achieve.

You will need a geomag stick (2 6x6x4 magnets) and a little bit of super glue. Please note that your printer must be quite precise as the tolerances are pretty tight (0.1-0.15mm), if printed with a bambu this problem is not present ;)

After printing everything, put a very tiny drop of super glue in each magnet hole and push the magnets in separately (be careful about the polarity: if placed with the same facing pole, the box will never close!). If the inner container is too loose, you can also add glue between the case and the bottom of the internal holder.