People print guns and gun parts. More than you think. Now even more since metal printing is starting to become affordable. I print grip and grip attachments for my 9mms and my AR15, trigger guards, barrel clamps, etc. I also find it stupid since, as the article suggests, what kind of algorithm can you implement to do smart detection of something that could be potentially dangerous? Will it also detect negative space? I print inserts in elastic filament with my gun outlines instead of foam (or as foam templates) for my carrying cases. Will the "algorithm" prevent me to do that too? What about my plastic disc thrower toy gun, or my PKD Blaster prop? Both look like guns to me. What about a dumb AI algorithm that lacks common sense?

Printing barrels and FCUs -- the fire control unit, which is the only thing tracked and serialized in a gun at least in the US -- is more difficult but not impossible. Actually, building a functional FCU that can strike a bullet primer, or a barrel that can be used once is not difficult at all and if you look around you can find videos of people that have tested that with a mixture of 3d printing and rudimentary metal working skills. The major issues on designing those parts are reliability and safety. In the Philippines there is a full bootleg gunsmith industry dedicated to build illegal guns that match commercial ones in those aspects too.

Sadly, instead of having better laws we get fallacy rhetoric by people who probably have never touched, much less fired a gun in their lives.