NEW YORK (CBSNewYork) – Mayor Michael Bloomberg has long railed against the flow of illegal guns into New York City.

But what will authorities do about theoretically untraceable guns that are made right here?

Popular Science magazine reported that an amateur gunsmith claimed in an online forum to have used 3-D printing technology to make the core component of a functional AR-15 assault rifle. The online forum user went by the handle “HaveBlue.”

The AR-15 is the same kind of rifle James Holmes is alleged to have used to carry out the worst mass shooting in U.S. history during a showing of “The Dark Knight Rises” in Aurora, Colo.

A 3-D printer is about the size of a small refrigerator and uses plastic and other substances to “print” objects by carefully layering the material. The printer follows detailed design instructions, typically downloaded from sites like

The New York Daily News identified the man who printed the gun as engineer Michael Guslick.

“I guess this is a testament to how fearful people are of hearing that someone can 3-D-print a gun without understanding that this wasn’t all that complex, it’s only in a legal sense that I have printed a firearm,” Guslick told the News.

On his blog, HaveBlue detailed many of the challenges and legal concerns in attempting to print the gun component. However, he wrote “It functioned perfectly.”

“Everything ran as it should, magazine after magazine,” he wrote.

Guslick doesn’t think that criminals are likely to take to printing gun components, however.

“Criminals are not going to give this a second thought,” he told the News. “They will continue to look to the black market, rather than saying ‘Oh gee, we need to buy a 3-D printer.'”

Are you concerned about the possibilities of home-printed weapons? Sound off in our comments section below.

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