Any new technology always seems to find its way into military uses.  There are tons of uses of 3D printing for military machinery parts, but there are also potential applications in the munitions themselves.  You may be familiar with shape charges,

where the explosive can be formed to direct its energy preferentially in a specific direction. 3D printing seems perfect for forming theses, assuming an explosive could be put in a “printable” form and printed safely. The idea of 3D printing bombs of course raises worries of illegal and terrorist use. In fact the great podcast “It Could Happen Here” with Robert Evens even took a deep dive in episode 5 as to how 3D printing technology could be used in an insurrection in multiple ways.

This is probably not a huge application anytime soon, but sure is an interesting one to think about. I guess its proof that people will find a way to put just about anything through a 3D printer eventually.