> The irony isn't lost on me that it's the USA, the country with some of the most permissive gun laws in the world, that's imposing these draconian rules on 3D printed guns - or is this pressure from the gun manufacturing lobby?

It's like saying "I am baffled by Europe, look at what Hungary is doing ..."

For example, some states don't need any permit to open or conceal carry, some have no minimum age requirements to buy guns, and the majority don't have any mention of 3D printed guns.

Federal law applies then about untraceable guns and or arms that cannot be detected by metal detectors. But those predate 3D printers as we know them today.