In what is thought to be the first such discovery, Greater Manchester Police officers found a plastic trigger (top image) and clip capable of holding bullets, which they believe had been 3D-printed using a MakerBot Replicator 2 that was also discovered at the property.
If verified, the discovery "demonstrates that organised crime groups are acquiring technology that can be bought on the high street to produce the next generation of weapons," said detective inspector Chris Mossop of the city's organised crime unit.
Update: Greater Manchester Police issued a new statement following these claims after the 3D-printing community pointed out they may be harmless printer upgrade parts.
"This is a really significant discovery for Greater Manchester Police," said Mossop. "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."
Forensic experts are analysing whether the parts found could be used to make a working weapon, but Greater Manchester Police already believe this is the first discovery of 3D-printed gun parts in the UK.
The world's first 3D printed gun was successfully fired in May this year by US anarchist Cody Wilson, triggering a global debate about the social and ethical impact of 3D-printing. Wilson's gun was acquired by the V&A museum in London last month.
"There's been a lot of technocratic optimism around 3D printing, particularly in the design world," senior V&A curator Kieran Long told Dezeen in an interview about the acquisition. "I don't believe everyone should be carrying guns and that's not what we're advocating here. What we are saying is this is possible and we might have to do something about it if we don't want these things to happen."
"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," said Mossop. "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."
MakerBot's Replicator 2 printer went on sale earlier this summer. Open-source designer Ronen Kadushin warned last year that 3D printers could allow people to "print ammunition for an army".
Read our feature on how 3D-printed weapons are transforming warfare.