Guns also are not manufactured clandestinely en masse, anywhere, because it takes a lot of precise industrial machining to do at scale. They are not like sex or weed that are impossible to ban, when you stop manufacturing them for nonsense reasons, they stop circulating and criminals stop being able to get their hands on them.

This is false. There are multiple Latin American countries where street gangs have been manufacturing reasonably sophisticated all-metal submachine guns at scale in clandestine factories for over a decade. Even prior to the 3d printing boom, open bolt submachine gun were fairly simple for an individual to manufacture with common hand tools, and quantities scale rapidly with improvised tooling and readily available machines like benchtop lathes.

With 3d printing, it has become even more accessible. Printers can be used to manufacture tooling in addition to parts, and the DEFcad community has been remarkably resourceful in developing new methods utilizing 3d printers. Everything from electrochemically etched, rifled, barrels to recoilless rifles with shaped charge warheads can be made at home if a person has no compunctions about breaking the law.

You can see the impact of 3d printing overseas, where there are a number of rebel groups using 3d printed firearms as their primary armament. Banning guns might reduce the quality of what is available, but it definitely won’t end production in a country full of gun enthusiasts with the interest and skills to make firearms.

I do not understand why Americans think they are such unfathomably unique snowflakes that none of the evidence or lessons learned from every other developed country could apply to them.

As I said, our gun culture ensures people continue to make firearms regardless of what the law says. We have countless machinists, gunsmiths, and hobbyists that would manufacture guns as a form of protest if they were banned. Furthermore, we already have more guns than people and the vast majority of them would remain in civilian hands if the government tried to seize them.

But most importantly, many Americans believe that the equalizing force of firearms—something that allows the citizenry to defend themselves against tyranny and for the weak/frail to defend themselves against the physically strong— is philosophically worth a small reduction in public safety.