It's not as though criminals have any difficulty obtaining firearms in the U.S., even in jurisdictions that have very tough gun laws. I strongly doubt that many criminals will go to the trouble of using 3D printers to make guns, when they can get guns so easily already.
Growing up in Chicago, I used to sweep bullet casings off the sidewalk in front of a community center where I was a volunteer. I lost two friends to gun violence before I graduated from high school. This was in a city that had a total ban on handguns.
When my dad was growing up in rural Michigan, there was a gun in every home, yet shootings were unheard of.
We would be wiser to focus on the causes of violence, rather than on access to firearms. I don't think 3D printing hobbyists are our biggest problem.
Thanks for covering this. The danger is more evident than some may realize, since 3D printing of metals has been around for a long time. Even if it can't yet be done in the strength required for guns, that's probably not so far away, since NASA is developing 3D printing technologies for making rocket engine parts http://www.designnews.com/author.asp?section_id=1392&doc_id=254513
It's always been legal to manufacture a firearm for personal use in the US, as long as you comply with the NFA 1934, GCA 1968 - meaning no restricted classes of firearms (automatic, suppressed, short barreled rifles/shotguns. Restrictions only come into play when you wish to sell them. Fear of home built weaponry used for evil looks to be a result of going out of your way to find something to be afraid of or the search for sensational storylines for ratings ("Tonight!!, 10 things in your home that may kill you....Details at 10" ). After all, you can go to the hardware store, buy some gas pipe, a spring and some fittings and build a zip gun in your garage in an afternoon – it won't be as effective as a pump shotgun but to paraphrase your own words: it only takes one round to kill. How about the fact that you can buy a black powder revolver without all the paperwork of a cartridge firearm? I guess the public is not as likely to be riled up over the availability of metal working tools that is being stirred up in the area of 3d printing.
The Undetectable Firearms law is perhaps the finest example of this level of silliness. This law was written after it was revealed that Libya had purchased an order of Glock pistols in the 1980's. This resulted in ignorant press featuring hysterical stories of "plastic guns that were invisible to airport xrays". Of course, the Glock showed up just fine on xrays since they contain a considerable amount of steel but still, Congress leapt into action to pass a law against something that does not exist. I'm still waiting for them to pass laws banning concealable rail guns or pocket plasma weapons.
The future tech of printing out useable objects is fascinating. However, by the time someone figures out how to 3d print a barrel capable of holding realistic pressures involved in pushing out a projectile at lethal velocities, the public will quite probably be more worried about the availability of Han Solo's blaster than antiquated firearms technology.
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