Police are warning technology enthusiasts not to attempt to use 3D printers to make plastic guns, because each time they have been tested the weapons have exploded.
Relatively cheap plastic printed guns have been fired successfully in the United States.
Scientists in the UK say without additional expertise and the right type of ammunition, anyone attempting to fire one would probably maim or even kill themselves.
They also point out that to do so would be illegal.
Phil Mackie, has been given exclusive access to tests which have been carried out by the National Ballistics Intelligence Service in Birmingham.