Additive manufacturing (of which FDM is one of the most accessible techniques) has been a MASSIVE funding source amongst world governments over the past 20+ years. And much of the research that made Reprap (et al) came out of scientists who specialized in those technologies for those grants.

Why? Because NO country is ready for a war. The US military is the most bloated military on the planet and Iran (and supporting Ukraine prior) has made it clear that we are desperately terrified of actually using our stockpiles.

Because, as Ukraine has reminded us, basically EVERYTHING is a consumable. The numbers get murky and depressing but I want to say I saw reports that small arms had a lifespan of less than a year under heavy use (either lost due to casualties or just degraded to the point that full replacement parts become a need). And if you roll back to the last time there was such mass industrialization to support war efforts… it is basically WW2. And there is a reason the guns in 1939 had wood furniture and were “built to last” and the guns in 1944 were basically stamped sheet metal where you were more likely to die of tetanus than lead poisoning (I mostly kid).

So what does that have to do with additive manufacturing? Because the push to convert factories meant basically ANYTHING with a lathe or even an early CNC machine were required and the only way to convert those factories involved incredibly expensive processes as essentially the entire floor was rebuilt and restructured to shift from cars to tanks or saxophones to stens.

Whereas additive manufacturing? Regardless of process, the Dream is that you just upload a new STL file and that gets you 90% of the way there. You still need to do some reconfiguring for finishing processes but it is MUCH MUCH MUCH cheaper. And, in theory, you can have the same factory output tank, jet, boat, and gun parts depending on the need.

And… from a homefront defense perspective, you can have hitler youth groups or resistance fighters making a lot of their own replacement parts in a closet rather than an automotive garage. Let alone print farms. Need a new upper receiver because yours caught a bullet? Go ask the kid from Home Alone 5 to print you one and you are back in action.

But, much like with drones, the inevitable happened. By using consumers to subsidize so much of the R&D work (there is a reason bambu et al insist that EVERYONE needs a multi-filament system and the ability to switch toolheads and…) means that the capability of the hobbyist caught up really quick. And, much like with drones, there is a frantic attempt to use legislature to put the genie back in the bottle.