(FOX 2) – A person already out on bond for a separate crime involving possession of controlled substances was arrested again for carrying a concealed AR-15-style firearm.

According to the Oakland County Sheriff’s Office, the suspect is now facing multiple charges after their gun violence task force discovered he was 3-D printing gun parts that turned firearms into automatic weapons.

Now, 13 devices used to convert Glocks into machine guns are off the street.

The sheriff said the devices, which look like harmless pieces of plastic, can turn a fully automatic weapon.

“So instead of pulling the trigger once for each shot, you pull the trigger and keep going until you run out of ammo,” said Sheriff Michael Bouchard.

The person, who has not been arraigned, was taken into custody by the Gun Violence Task Force over the weekend. After arresting him, the task force seized a 3-D printer as well as the modified devices.

“The individual, we believe, also bought them elsewhere in addition to coming up with his own process,” Bouchard said.