I'm not going to pretend to be an expert on printing 3D guns, but I consider myself at least as well informed as the lawmakers that are throwing a hissy fit about the new technology.
Let's start off by discussing what's been done thus far. A few gentlemen have used hard to find $8,000 printers to make AR15 lower receivers, and complete .380cal and .22lr handguns.
The handguns were single shot firearms with almost no steel needed in their manufacture. The AR lower receiver seemed to work OK in limited testing.
People were already making their own AR lowers before this printing technology was invented. Others have been making AK receivers. I'm not going to link to the sites that show how (it's covered in earlier posts). They're easy to find if you're interested. Google is your friend.
The only difference is that now some geek with a printer can produce what a shade tree mechanic has been able to make with a CNC machine and hand tools.
It's just as legal as it's always been. Nothing's changed despite the news articles, speeches from politicians, and fear mongering.
If you're able to currently own guns, then you can legally produce a homemade firearm for your own personal use. It cannot however, be sold, or given away. Of course state laws vary on this topic, so what's true in one state may not apply to some Liberal utopia such as California or New York.
While it's true that almost a complete handgun was produced from one of these 3-D printers, it's also true that they were inaccurate single shot weapons that weren't trusted to stand up to a lot of testing.
Long story short... it cost about $8,000 to produce a plastic gun that will do the exact same thing that a $30 zip gun made from parts purchased at Lowe's will do. That's not entirely true. The $30 zip gun would probably be safer. Again, the videos are on YouTube. I'll let you do the research.
The technology for these printers will no doubt improve. Prices will eventually drop. Will they become affordable for the average person? Time will tell. Even if they drop to the price level of a computer or television, it would still be more cost effective for a criminal to buy his gun on the black market.
Let's recap where we are with 3-D printed guns:
1) They're a novelty, and good luck finding someone currently willing to put 300 rounds through one (the break in period for most handguns). You couldn't pay me to hold one while shooting even 5 rounds through them.
2) They're inaccurate.
3) They are single shot weapons, and use under powered rounds such as .22lr and .380acp.
4) You need about $8,000 worth of equipment to build one.
5) You can build a single shot handgun for under $30 with parts purchased at Lowe's.
6) The 3-D guns are fugly.
7) People are already building their own guns without $8,000 printers. This includes AK47's and AR15's.
8) It's already legal to make firearms for your own private use (depending on your location).
9) They may get through a metal detector. This is the only real concern.
10) You can buy a 6 shot cap and ball revolver for well under $300. No paperwork is needed in my state for this purchase as it's a primitive weapon using blackpowder. Civil War era technology seems to trump 21st century 3-D gun tech.
The printed guns are interesting, but hardly the end of the world as some legislators believe. I'm reminded of the 1980's, and when Glocks began coming to America. We were told that these polymer framed guns would pass through metal detectors. The public was lied to then, and I have no doubt that we'll see a great many lies told about these printed guns.
There is one, and only one worry about these plastic 3-D guns. It appears that if you make an illegal printed gun (without the amount of metal required by law), then it may pass through a metal detector. I suppose that someone could print one of these weapons, and possibly pass through a security checkpoint. Of course he/she is still stuck with a single shot weapon that may blow up when used.
Call me crazy, but I'm just not that worried about a criminal with a 3-D gun. They just aren't gaining anything from the new technology. Will that change in 10 years?
The genie is out of the bottle, and the technology and equipment is already in the real world. Half truths, hysteria, and poorly written laws aren't going to change that.