Free blueprints that allow anyone with a 3D printer to make a plastic handgun that fires real bullets have been taken offline after an order from the U.S. Department of Defence, says the man who posted them online.

Cody R. Wilson, a 25-year-old University of Texas law student, confirmed Thursday afternoon on Twitter that Defcad, the site where the blueprints for the Liberator pistol were posted starting last weekend, is "going dark" at the request of the Department of Defence Trade Controls.

A message at the top of the Defcad website Thursday states: "Defcad files are being removed from public access at the request of the U.S. Department of Defence Trade Controls. Until further notice, the United States government claims control of the information."

Defcad is dedicated to sharing weapons-related 3D printer blueprints and is run by a Texas-based non-profit group founded by Wilson called Defense Distributed.

The gun is made entirely of plastic except for a metal firing pin, making the pin the only part of the gun that would be detectable by a metal detector. That caused a lot of controversy, and caused at least two U.S. politicians to speak out against the project.

Defense Distributed, which says its goal is to challenge gun laws, posted a video of a successful test firing of the Liberator pistol this weekend, just prior to posting the blueprints online.

A 3D printer can take those blueprints and use them to replicate individual parts of the gun by depositing plastic layer by layer. The parts can later be assembled into the complete gun.

'A gun's a gun,' says security expert

"So really, all you need is a $1,000 3D printer and you could produce the parts," said Michael Legary, a Winnipeg-based security expert whose work involves creating anti-virus software for companies and law-enforcement agencies.

Winnipeg-based security expert Michael Legary holds plastic pistol parts that were produced by a 3D printer. (Karen Pauls/CBC)

"It's crude. A gun's a gun, though. This one device could kill someone."

Alarmed by the availability of the blueprints, Legary has developed a "hash," a kind of digital fingerprint that would detect the presence of 3D printing instructions for plastic pistols.

"These files are being downloaded within schools, within large businesses, and they're being produced on equipment unauthorized," he said.

"So we want to be able to detect those files and remove them from the networks and from the environments before they have a chance to be printed … and control the printer from producing these weapons in the first place."

In Canada, it is legal to download the instructions, but there is a question of whether Canadians can legally print the components.

Legal debate

The possession of a firearm is illegal without licences and registrations, but it's not certain at what stage of the plastic guns' production they would be illegal, if at all.

"The average citizen doesn't know … how to manufacture a gun, but they know how to click Print," Legary said.

"They conceive that because they can click Print, they must be allowed to."

Tony Bernardo of the Canadian Shooting Sports Association says he doesn't think it's necessary to track those who download the 3D plans or print the gun components.

"The right to information and the information flow is something that Canadians prize pretty highly," he said.

"I don't think that the government stepping in and restricting the flow of information because somebody might do something wrong is a very rational reaction to this."

Clayton Ruby, a civil-rights lawyer, sees both sides of the debate.

"The proliferation of guns in this way is just frightening, and it's something the government's got to take control over," he said.

At the same time, he added, "I don't know that I want to say we are entitled to invade everybody's privacy to the point of monitoring their printers, because that's massive overkill."