I wonder if fire-proof could be done. Seems like the waterproofing is from a simple but quality rubberized seal?
Discussion
Fireproofing is probably beyond what I can do with a 3d printer. Going to try to design a seal to print with TPU -- if you look closely the groove is already there where the two halves of the shell meet.
You can always make it a pattern and use the 3d print as a prototype for other materials. I don't know if there's a high temperature resin/reinforcement system that would withstand fire and inside would get roasted anyway.