At the South Philadelphia high-tech makers’ space NextFab, creators of all types work on projects using laser cutters, robots, and a room full of 3D printers.

Walt Barger, who manages the printing operations there, is standing between two printers the size of refrigerators, noting both their power and price tag.

“It’s an older printer, but it’s still a $40,000 machine,” he said, pointing to one. “And the one next to it, the ProJet, is a $100,000 machine.”

Lately, Barger has been extra vigilant about the kinds of things people are hoping to create here.

“Our staff is always monitoring. If we see anything that even looks like a gun, we’re going to stop the person,” he said.

Barger hasn’t had to do that yet, but he says the company makes its policy clear to new users: don’t even try.

“If you’re going to 3D print any parts of a gun, since people are coming in here and using our equipment to print, we then have a liability,” he said.

People who work in the 3D printing industry in Philadelphia and around the country are taking action against 3D-printed guns.

This comes after attorneys general in Pennsylvania and New Jersey sued to stop one website from sharing 3D gun blueprints. That prompted a federal judge to block those blueprints from being accessed online.

Even though thousands downloaded them before the court stepped in, experts say that shouldn’t cause widespread public safety concerns.

Barger and many others who work in the 3D printing believe the threat is being overblown.

Printing out a fully functional 3D gun is not a simple feat. It could require a $10,000 printer. Technical chops are necessary — not to mention hours and hours of trial and error.

For those hoping for the day when making a homemade gun takes hitting the play button on a desktop printer, Max Lobovsky has some news to share.

“It’s far enough away from now that we’d have a low-cost device that can produce a fully functional firearm. I don’t think anyone is particularly close,” he said.

And he would know. Lobovksy is the CEO of Formlabs, a $1 billion 3D printing company out of Massachusetts.

“I mean, I think we’re at least 10 to 15 years away,” he said.

Still, some 3D printing companies are already on the defensive.

Major 3D printing company Sculpteo has banned firearm printing.

“We are forbidding firearm printing for ethical reasons,” reads a statement on the website of the France-based company, which also has a branch in San Francisco. “We don’t support firearms and weapons manufacturing.”

And Materialise, a publicly-traded 3D printing manufacturer and software developer, has launched a feature to block the production of guns, according to a company spokesman.

“The analogy that I think is really useful here is efforts that have been taken to prevent counterfeiting,” said Chelsea Parsons, a gun policy expert at the Center for American Progress.

Adobe Photoshop has tried to clamp down on people using the software to generate fake money. Likewise, Parsons says it makes sense that 3D printing businesses are trying to get ahead of the issue.

“To say, your technology is being used for a purpose you certainly didn’t intend. That purposes poses risks to our communities,” she said.

Even though the risk isn’t immediate, gun-control advocates like Parsons say to airlines, courthouses, and other places with tight security, the idea of a plastic gun slipping through a metal detector is a real fear.

And if a 3D-printed gun got in the wrong hands and someone used it carry out violence, there could be an avalanche of lawsuits brought against makers of 3D printing machines.

“If I were a 3D printing manufacturer, I would certainly be thinking about this. Quite a bit,” said Tom Baker, a law professor at the University of Pennsylvania who specializes in liability and insurance issues.

Lawmakers in Washington are also thinking about this. Two bills have been introduced in the Senate hoping to make it harder for people to use printers to create fully functional guns.

Lobovsky of the 3D printing firm FormLabs said in the event of a 3D gun tragedy, he doesn’t think technology companies should be to blame.

“We shouldn’t be responsible for that any more than a company that makes knives is responsible for someone who commits a crime with a knife,” Lobovsky said.

If such an event ever happens and a civil lawsuit is lodged against a 3D printing company, law professor Baker says the issue of who took proper safeguards will be important in court.

After the 1993 World Trade Center bombing, a fertilizer company was sued for negligence for not taking enough steps to stop its product from being an explosive ingredient. The suit wasn’t successful, but Baker says a case against a 3D printing company might have a better chance.

“And so the question — and this would be a jury type question — is were there reasonable steps that could’ve been taken and weren’t taken?”

While Parsons admits that given what it takes to make a 3D gun, compared to how easily available illegal guns are on the black market, homemade weapons are not likely to become the dominant weapon for criminals any time soon. But she said with time and innovation, at-home 3D gun production will only get easier, a prospect that should be putting policymakers and technology companies on high alert.

“As the price comes down on these printers, and as the quality of what you can create with them improves,” Parsons said, “it opens up a whole new set of folks who are going to be able to make guns at home with very little skill required.”