The Sten submachine gun was designed in 1940, when the British army had to replace the weapons it had lost at Dunkirk. It “paired a simple design with a low production cost.” The most basic model, the Mark III, could be produced from five man-hours of work. Some of the cheapest versions had only 47 parts, and only the barrel and the bolt were machined.
In 1942, a Sten cost £2 6s to make. Soldiers called it the “Plumber’s Nightmare” and the “Stench Gun.” Around four million were made in the 1940s.