New York City's counterterrorism chief on Sunday called the threat posed by 3D printed guns "truly unbelievable."

"This is just insanity," John Miller told New York AM 970's John Catsimatidis on "The Cats Roundtable."

"The idea that we have fought … [for] a law where people who buy guns have to undergo a universal background check — that took years to get done," Miller said. "And we’re still [fighting to close loopholes on that law] even though we have a school shooting or a massacre every other week."

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"The idea of while we are fighting to close those loopholes, to then open the greatest loophole of all, which is buy a $2,000 printer and you can make as many guns as you want that aren’t subject to regulation; that don’t have to have a serial number, that don’t have to be traceable, that may not be made out of metal and can defeat certain metal detectors — we're taking a turn there from the ridiculous to something that is totally unbelievable." he continued.

The debate over such firearms, also called "ghost guns," was reopened last week when a federal judge blocked the online release of blueprints for multiple models of 3D printed guns.

The injunction came in response to a lawsuit from eight Democratic attorneys general who said the public distribution of downloadable guns unconstitutionally infringes on states’ rights to regulate firearms.

Supporters of 3D printed guns insist they are an issue of First and Second Amendment rights, while opponents insist they pose a serious public safety threat.

As the technology currently stands, it is extremely arduous and expensive to print a gun. The 3D printers that print effective firearms can cost up to millions of dollars, and the process takes upwards of 90 hours.

Indiana University law professor Jody Lyneé Madeira, who specializes in the Second Amendment, told The Hill over the weekend that gun kits, which allow people to assemble firearms in their homes, are a far more pertinent example of guns that do not require background checks.

"One of the most perhaps unregulated ways people have been making guns at home is through kits that they get," Madeira said. "The kits that people can get to build guns at home actually make weapons that are much more effective and dangerous than most of the firearms that can be printed by 3D printers."

3D printers that cost a few thousand dollars are often only capable of printing plastic guns, which are prone to shattering.

The case over posting the 3D printed gun plans will go back to court on Aug. 10.