U.S. Sen. Chuck Schumer says he’s seeking an extension of the law before it expires Dec. 9.

He said the technology of so-called 3-D printing has advanced to the point anyone with $1,000 and an Internet connection can access the plastic parts that can be fitted into a gun. Those firearms can’t be detected by metal detectors or X-ray machines.

Schumer says that means anyone can download a gun cheaply, then take the weapons anywhere, including high-security areas.