UPDATE: Greater Manchester Police have released a statement admitting the seized 'firearm' might not be a 3D printed gun, as first reported, and said they are now conducting "further forensic testing by national ballistics experts" as they "cannot categorically say we have recovered the component parts for a 3D gun".
Police in Manchester have made the chilling discovery of what could be the UK's first ever 3D printed gun factory - even as some claim that the parts are actually spares for a printer.
Police believe the parts represent the "next generation" of firearms, which can be created by gangsters and smuggled with ease due to the fact they can avoid X-ray detection.
It might sound like science fiction, but 3D guns have been a reality for more than a year. More than 100,000 people downloaded plans for an early prototype within hours of its release in May, and the V&A museum in London has already acquired some samples for its collection.
The technology works by allowing anyone who has a 3D printer - which can be bought on the high street for about £1,200 - to download designs for guns or components.
However reports have since emerged that the parts might actually be spare parts for a printer - and not a 3D gun at all.
Scott Crawford, head of 3D printing firm Revolv3D, told PC Pro that he recognised the parts from a totally benign 3D printer.
"As soon as I saw the picture... I instantly thought 'I know that part'. They designed an upgrade for the printer soon after it was launched, and most people will have downloaded and upgraded this part within their printer. It basically pulls the plastic filament, and it used to jam an awful lot."
This could be a component of a 3D printed trigger
3D printers squirt molten plastic to produce 3D shapes of whatever design has been downloaded.
The model parts can then be converted to become anything - including, in some documented cases, a genuine firearm capable of firing bullets.
The parts were discovered, along with a 3D printer, when officers from Greater Manchester Police executed a series of warrants in the Bagley area yesterday.
Police found what they suspect to be a 3D plastic magazine and trigger which could be fitted together to make a viable 3D gun.
If they are found to be viable components for a 3D gun, it would be the first ever seizure of this kind in the UK, police said.
The parts are now being forensically examined by firearms specialists to establish if they could construct a genuine device.
In June, the world's first 3D printed gun fired its first shot, created by Defense Distributed, a controversial company pushing for D-I-Y weapons.
The Manchester raid was part of Challenger, the largest ever multi-agency operation to target organised criminality.
Detective Inspector Chris Mossop, of Challenger's Organised Crime Coordination Unit, said: "This is a really significant discovery for Greater Manchester Police.
"If what we have seized is proven to be viable components capable of constructing a genuine firearm, then it demonstrates that organised crime groups are acquiring technology that can be bought on the high street to produce the next generation of weapons.
"In theory, the technology essentially allows offenders to produce their own guns in the privacy of their own home, which they can then supply to the criminal gangs who are causing such misery in our communities.
Because they are also plastic and can avoid X-ray detection, it makes them easy to conceal and smuggle."
He added: "These could be the next generation of firearms and a lot more work needs to be done to understand the technology and the scale of the problem.
"If what we have seized today can, as we suspect, be used to make a genuine firearm then today will be an important milestone in the fight against this next generation of homemade weapons.
"I would strongly urge anyone who has information about the whereabouts of a gun in their community to call us."
A man has been arrested on suspicion of making gunpowder and remains in custody for questioning.
Iain Overton, Director of Policy and Investigations at Action on Armed Violence,wrote on the Huffington Post recently:
"In just a few months, the possibilities of 3D printing of weapons have grown from producing individual firearm components to a single-shot pistol, then to a rifle and now to a multiple-shot weapon.
Even more worrying is the fact that these advances are being made by gun enthusiasts without any effective oversight by the authorities.
Fortunately, we still have time to address the problem, because for all their potential, 3D printers are still relatively rare. In short, they won't put Smith and Wesson out of business anytime soon."