Another approach, however unlikely, might be to simply make it illegal for people to build their own firearms, Winkler said.
3D printing technology is advancing. The topic even attracted attention at this year's South by Southwest Interactive festival in Austin. The technology conference's opening keynote was delivered by Bre Pettis, CEO of 3D printing company MakerBot, which offers units both for copying existing 3D objects and for printing models designed with computer software. MakieLab, a 3D toy printing company, was also present at the show.
The technology is still developing, with the units carrying a price tag often in the thousands of dollars. Those barriers notwithstanding, some worry that Defense Distributed's work could make it easier for guns to fall into the wrong people's hands.
"Teenagers, people convicted of felonies or who have drug and alcohol problems, and criminal enterprises ... This is a step in the wrong direction if it makes guns more available to them," said John Donohue, a professor of law at Stanford.
In particular, "troubled teenagers could see this as the next 'cool thing,'" he said.
Until the technology is perfected and becomes more widely available, it will probably only appeal to a small subset of the most vigorous gun enthusiasts, "but over time it could become a common way to make your own firearm," UCLA's Winkler said.
On the legislative side, political action on 3D gun printing from either Congress or the Obama administration probably won't happen any time soon, experts say. But Washington needs to get on top of the issue before the technology becomes widespread, Winkler said.
Others say that there probably won't be any legislative action until there is a tragedy involving 3D-printed guns.
"I doubt we'll see any major federal initiatives until something goes wrong," Stanford's Donohue said.
Legislators may have enough on their plates already. Senator Dianne Feinstein of California has been pushing for an assault weapons ban that would prohibit the sale and manufacture of 157 different military-style assault weapons, though on Tuesday, Senate Majority Leader Harry Reid said that measure would not be included in an upcoming gun bill.
Defense Distributed opposes Feinstein's efforts and has been following them closely. The group even named its 3D-printed AK-47 magazine the 'Feinstein AK Mag.' Feinstein could not be reached for comment on this story.
However, the gun-control debate as a whole is likely to dwarf the issue of 3D-printed guns. With more than 2 million background checks conducted each month for traditional gun sales, said UCLA's Winkler, "individually produced firearms do not make a big dent in America's stock of guns."
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