The pistol, capable of firing a deadly 0.38-calibre bullet, was produced in under 36 hours using a revolutionary £1,700 machine to 'print' its components. And because all the parts are plastic, they did not trigger the metal detectors all Euro-star passengers must pass through.
Last night, the train operator began an urgent investigation into the security breach as experts called for airports and public buildings to review their procedures in light of our revelations.
The Mail on Sunday pieced together the 16-part pistol – called The Liberator by its creators – after downloading the designs. They were originally published by an American university student, who proved the design works by successfully firing a bullet on a shooting range.