The government is concerned about the proliferation of 3D printed guns. That much was obvious when the State Department demanded Defense Distributed remove the blueprints for the first 3D printed gun – The Liberator – from its Web site. Now another government agency is warning law enforcement about the potential dangers posed by 3D printed firearms.

Fox News reports that the Department of Homeland Security has issued a bulletin on 3D printed guns to law enforcement agencies around the nation. It says that 3D printed guns in their current state may be “impossible” to stop. The DHS continues by saying that it can’t regulate the guns because it can’t regulate the file sharing that’s putting the gun’s blueprints in peoples’ hands.

Like other agencies, the DHS is concerned that people will use 3D printed firearms to get past metal detectors. Their main concern is that large events will be harder to police since magnetometers, which are used to find metal weapons, will be useless against 3D printed weapons.

An anonymous law enforcement official told Fox News that the only solution to the potential threat is to pat-down every single person attending any large event. He ends by asking if America is ready “for pat-downs at every event.”

Near the end of the memo, the DHS says that Congress can pass laws banning 3D printed weapons. The agency admits that it probably won’t stop the creation of 3D printed guns though:

“Even if the practice is prohibited by new legislation, online distribution of these digital files will be as difficult to control as any other illegally traded music, movie or software files.”

We’ve seen over the past few weeks that people are already experimenting with the Liberator and making it better. Some are even making 3D printed bullets. The DHS does have some legitimate concerns, but it’s hard to say just how much of a threat 3D printed guns pose at the moment. It seems that hobbyists and gun smiths are the only ones interested in the technology for now. Besides, the liberator isn’t much of a gun, and is still prone to exploding.