A plastic gun made in a 3D printer fired real bullets during demonstrations over the weekend. Texas-based Defense Distributed has just made the blueprints for the gun available free so it can be replicated by others in their own 3D printers.

The non-profit group, which says it aims to challenge gun laws, posted a video of a successful test firing of its Liberator pistol on its blog Sunday. The group held demonstrations for the media at a Texas firing range this on Friday and Saturday.

The pistol is made of plastic using a 3D printer, which deposits the material layer by layer by squirting it out as it scans across, line by line, the way a regular printer does. Its only non-plastic part is a metal nail that is used as a firing pin — the only part of the gun that would be detectable by metal detectors used to check for weapons.

The video invites people to download the CAD (computer-aided design) file for the gun from a website called DEFCAD.

The file is available for free. However, anyone who tries to download the file is invited to donate money to the group's "Wiki Weapon" project.

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Individual components of the gun are made of plastic by depositing the material layer by layer using a 3D printer, according to downloadable blueprints. (Defense Distributed)

Defense Distributed has previously posted a video of someone firing a gun with certain key parts that were made in a 3D printer, but this is its first time it has made available a blueprint for an entire, working 3D printable gun.

In addition to the Liberator pistol, Defense Distributed's DEFCAD website also hosts other weapons-related 3D printer designs that were banned from Thingiverse, a popular website run by 3D printer-maker Makerbot Industries for sharing 3D printer blueprints.

Defense Distributed is headed by 25-year-old University of Texas law student Cody Wilson. A list of frequently asked questions posted on the group's website says its project is about challenging gun control and regulation.

"We look to inspire and defend those who live (and are threatened to live) under politically oppressive regimes," it adds. "Firearm rights are human rights."

In response to the question "Why guns?" the site explains, "If we truly believe information should be free, that the internet is the last bastion of freedom and knowledge and that societies that share are superior to societies that censor and withhold, then why not guns?"

Illegal outside U.S.

The site says that while it is legal in the U.S. to fashion your own firearm and talk about doing so, people in other countries should "proceed with the expectation that every bit of this is illegal."

According the RCMP, in Canada it is illegal to manufacture or possess a firearm without appropriate licences and applicable registrations.

"If law enforcement found an individual in possession of a 3D printer-manufactured firearm or parts of a firearm (e.g., magazines, barrels), without appropriate licences and registration, the firearm could be seized and the individual charged," said RCMP spokesman Sgt. Greg Cox in an email to CBC News.

He added that the RCMP is monitoring developments related to the 3D printer technology for making guns.

Meanwhile, the Liberator gun has drawn concern from some U.S. politicians. On Friday, following a media demonstration, New York Congressman Steve Israel issued a statement calling for the extension of a U.S. ban on all-plastic firearms, which expires this year.

"Security checkpoints, background checks, and gun regulations will do little good if criminals can print plastic firearms at home and bring those firearms through metal detectors with no one the wiser," the statement said. "When I started talking about the issue of plastic firearms months ago, I was told the idea of a plastic gun is science fiction. Now that this technology appears to be upon us, we need to act now."

The ban does not apply to the Liberator because of its metal pin. However, Israel expressed concern that "those who wish to smuggle guns onto planes and into high security areas" will be able to download Defense Distributed's blueprints, "forgo" the "extraneous" metal pin, and have an undetectable gun.

At a news conference Sunday, New York Senator Charles Schumer called for a law to ban making guns using a 3D printer.