Ban 3D printers? That's not going to happen. Seems the TSA did their job.

I once had a bottle of vitamins confiscated because - well, how the hell do I know. This yahoo should have certainly known better than to pull a stunt like that.

Unless maybe there's a reason to want a gun with zero history.

If you can't find a straw buyer for it, or some other source, you're pretty much out of your chosen profession. But if you can get online and download the schematics, you're covered.
yay technology.

...then buying the gun legally is the least of your problems.

you grabbed your razor, travel sized shampoo, tooth brush, but you left your brain sitting at home.

People can check on rifles, and do so all the time. Just noting that there is a key difference.

Firing pin is metal and most designs use metal barrel or at least a metal chamber as plastic tends not to hold up to firings. The ammo is also metal. So plenty of metal to set of metal detector.

There are also 3D printed metal guns which can be printed using metal powder and lasers that are far more capable but they are obviously metal.

1. Curiosity. A lot of the Maker community likes to push technology to its limits. One of the limits of 3D printing is whether you could actually make such a gun work, and not blow itself apart.

2. Preppers/paranoiacs. A subset of people trying to make guns like this expect that any day the goobermint is going to take away their toys, or civilization will come to an end and they won't be able to get one. Solution? Make guns. Never mind that in any scenario where civilization falls apart you won't have the materials or electricity to run a printer... or that if the goobermint was going to grab their guns, officials would have the brain power to also track purchases of the necessarily very large amounts of the materials used to make relatively well working printed guns.

3.

Ok, there isn't a real #3. You don't need to print a gun to erase its history. Either way, illegal, so why not just buy one and remove identifying marks. Really, most people actually doing it are hobbyists who both like guns and are fascinated by the potentials of 3D printing.

At best, it's just another manufacturing method. In time, I'll bet that most small goods will be made this way, at least in part, by a lot of companies.

3D printed guns do not pose any additional danger - except to anyone dumb enough to use them. They're really good at flying into pieces. If you want to ban 3D printing because someone made a stupid plastic replica, which was easily detected, you might as well go all the way and start advocating that nobody be allowed to make anything at all at home. After all, someone might carve a great replica gun!

People can easily build guns, and they don't need a 3D printer to do it. It's already illegal.

even if the gun is plastic, the ammunition would be metal. I would hope the metal detectors would get it. And if it's in a bag then the visual screeners would hopefully see a gun shaped object and check it out by hand.

Since they let him go without punishment, I can definitely guess what he looked like.

And any other tool that can be used to make stuff.

and files
and sandpaper
and sheetmetal

That alone is a story.

That was one of the limiting factors in building an all-plastic gun: you need metal springs to get the action and magazine to function on a plastic semi-automatic handgun.

Now if the firing pin were made of a plastic hard enough to set off the primer in the cartridge, it would be entirely metal-free (except for the actual ammunition).