I made the ultimate Microbit set for my purposes. I combined several kits in to one kit, and also included a ES121 electric screw driver and tweezers.
I found a good sturdy case for fishing flies.
I found out that a common laser cut friendly foam is polyethylene foam (PE foam or PEF). It’s commonly used for tool cases.
I calculated all the bits I wanted, and made slots for them together with some of my tools. Then I laser cut them out and hot glued them into place the case.