While researching for one of my old projects, the electronic grenade (Part 1 & Part 2), I experimented with a very different design. Instead of 3D printing the enclosure, I tried 3D printing a negative and molding the enclosure with liquid rubber. To be exact, it was a pair of liquids that hardened when combined.
The proof of concept was relatively successful. Parts could be molded with excellent precision, and since they were made of rubber they could withstand being thrown better than 3D prints ever could (except maybe rubber filament).
The problem was that the molds were much harder to design than the actual piece, and tended to break easily when demolding due to the rough surface not sliding very well.
In the end I discarded this route. However, I did find a neat example of such a grenade online at the following website which documents many types of grenades and other explosives: