Senator Charles Schumer wants to ban a new type of plastic gun that fires real bullets.
He says a non-profit group used a 3D printer last week to make the weapon for the first time and plans to put the instructions online this week.
Schumer says plastic guns are legal for now, but are especially dangerous because they can easily slip past metal detectors.
He wants to strengthen a ban on undetectable guns by extending it to cover the making of plastic weapon components.
"We're facing a situation where anyone -- a felon, a terrorist -- can open a gun factory in their garage and the weapons they make will be undetectable. It's stomach-churning," Schumer said.
Three dimensional printing has been around for about a decade, but has recently come into wider use in the health care and manufacturing industries.