Necessity is the mother of invention. The point has been proved for many years. For the convenience of the people, everything is available in the market today. Whenever man missed something, made him. But you will not know that many things are built by prison inmates, who can surprise anyone.
Soap pistol:
Year in 1930, while in jail prisoner named John Dilinjrs pistol had designed. John murder and was jailed in the crime of robbery, but while the size of the prisoner soap pistol ready, so that they could ultimately help people run scared. The first of these prisoners had tried to escape several times.