An 18-year-old San Jose man was arrested for allegedly using 3D printers to assemble an arsenal of ghost guns, the Santa Clara County District Attorney’s Office announced Thursday.

Authorities found two working 3D weapon printers and 27 finished or almost finished guns in Jacob Reyes’ bedroom at his family’s home on Peach Court, the district attorney’s office said. Some of the firearms were modified to be machine guns.

“There is a black market of weapons thriving right under our noses,” District Attorney Jeff Rosen said in a statement. “Once again, the DA’s investigators and their law enforcement partners have taken off the streets an arsenal of untraceable, illegal, and deadly weapons.”

Reyes was slated to be arraigned Thursday afternoon. He faces felony charges of possession of a machine gun, other related felonies and charges related to the unlicensed manufacturing of firearms using a 3D printer, according to the district attorney’s office.