The PPS-43 was made during the seige of Leningrad. It was made in a tuba factory initially, out of sheet metal stampings and spare parts of PPSh-41 submachine guns whose wooden stocks had been burned for heat. It was a quite successful and effective weapon, and since it couldn't be burned or eaten, it was put into production so fast and amazingly numerous that it became useful even after the siege had broken.
Still a damned ugly looking gun, though. :)