Volume 3 of Professor Parabellum's Practical Scrap Metal Small Arms.
This volume provides plans and instructions on creating a 100% DIY STEN-style submachine gun. No lathe or milling machine is required - this can be built using basic power tools.
"The DIY STEN Gun is a simplified 1:1 copy of the British STEN MKIII submachine gun. The main differences however include the number of components having been greatly reduced and it's overall construction made even cruder. Using the simple techniques described, the need for a milling machine or lathe is eliminated making it ideal for production in the home environment with very limited tools."