In the wake of the worst mass shooting in US history, many Americans want to ban civilians from buying the AR-15, that ultra-popular, all-American killing tool. But in basements and garages around the country, another group of Americans is collecting the machines and materials to make those firearms in the privacy of their own homes. And for them, just as much as for gun control advocates, Orlando represents a call to arms.

Senate Democrats reacted to the massacre by filibustering until Republicans agreed to allow a vote on four gun control measures. Every measure failed on Monday night. But even fears of such legislation have lead gun owners to stock up on guns and ammunition after every mass shooting in recent history. And now a newer trend has emerged in the days since Omar Mateen killed 49 people with a handgun and a Sig Sauer MCX rifle: sales are spiking for the equipment and materials used by DIY gunsmiths to make their own, fully-functional, semi-automatic weapons.

Using power tools, chunks of aluminum, and cheap, consumer-grade digital gadgets, those firearm-focused members of the maker movement fabricate homemade weapons like AR-15s and AR-10s that skirt all regulation and would be untraceable in some imagined, future crackdown in which the government were to seize registered weapons. "People are hopping off the mainstream train and accepting an underground dissident mentality when it comes to guns," says Cody Wilson, the founder of the Austin, Texas-based DIY gun group Defense Distributed. "They're making the connection: If [an AR-15 ban] is enacted, I can get this machine and make one anyway."

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Since the fall of 2014, Defense Distributed has sold approximately three thousand of the $1,500 devices it calls the Ghost Gunner, a computer-controlled, one-foot cubed milling machine designed to let anyone carve their own aluminum body of an AR-15 at home. Since all other parts of the gun can be bought without any regulation, the result is a lethal weapon that's free from background checks, waiting periods, serial numbers, or any other government involvement.

On a typical day, Defense Distributed sells four or five of its gun-making machines, according to Wilson. But on the day after the Orlando gun massacre, it sold seven. The second day after the killings, as Democratic senators were filibustering, it sold 11. In all, Defense Distributed's total revenue has jumped from around $30,000 a week to more than $50,000 last week, the most sales it's seen since the hype around the Ghost Gunner's initial launch 20 months ago.

Older methods of making an untraceable AR-15 are exploding, too. Santa Ana, California-based 80 Percent Arms, for instance, specializes in "80 percent lower receivers": bodies of AR-15s and AR-10s that are left 20 percent unfinished and thus unregulated. DIY gunsmiths can complete that last bit of machining themselves, with tools ranging from a Ghost Gunner's automated milling to a simple drill press and a set of jigs. The day of the Orlando shooting, 80 Percent Arms' sales spiked fivefold, then sixfold on the day after and sevenfold the day after that, says the company's president Tilden Smith. "When Obama gets on the air talking about gun control, that kicks off a buying frenzy. Everyone flips out," Smith says. "They're incentivized to get all the 80-percent stuff they can now, because they don't think they'll be able to get it next year."