The £16 gun: Plastic firearm you ... Defense Distributed used a higher-end $8,000 (£5,250) model to build its 3D gun. However entry-level desktop models can cost $500 to $1,000 (£329 to £659).

Once Wilson has printed the gun and ensured that it works, the weapon's 3D model files will be uploaded to the internet and open sourced -- so that you and I can print an almost-undetectable firearm.