Probably a good idea to renew this one.
Check this out:

Guns that cannot be detected by X-ray machines will no longer be banned if Congress does not renew the decades-old prohibition by Dec. 9.

The 1998 Undetectable Firearms Act will sunset that day, ending the prohibition at a time when new technology has made it easier than ever before to manufacture plastic guns with 3-D printers.

Gun control activists warn that a lapse would allow anyone with a few thousand dollars to build a homemade gun that would be undetectable at airports, government buildings or schools.

That threat was little more than “science fiction,” when Congress overwhelmingly backed the ban 25 years ago,” said Rep. Steve Israel (D-N.Y.), who is pressing legislation to renew the law.