A plastic magazine and trigger, which could have potentially been fitted together to make a gun, were seized by police in Manchester along with the 3D printer that created them.
The components are now being examined to see if they could have been fitted together to make a viable 3D gun.
The technology works by allowing anyone with a 3D printer - which can be bought on the high street for £1,200 - to download designs for guns or components.
A man has been arrested on suspicion of making gunpowder and remains in custody for questioning, Greater Manchester Police said.
A 3D printer, which police believe criminals may have been using in an attempt to create a firearm, has been seized in Manchester.
Greater Manchester Police and Trading Standards officers have carried out a number of raids in their biggest operation yet to tackle organised crime.
More than 50 arrests have been made in a week long crackdown on illegal money lenders, drug dealers and counterfeit goods suppliers.
Challenger is the largest ever multi-agency response to tackling organised criminal gangs in Manchester's history.
More than £330,00 worth of drugs were recovered, £25,000 in cash seized along with weapons including high powered air rifles and a Taser.