Volume 8 of Professor Parabellum's Practical Scrap Metal Small Arms.
This volume provides plans and instructions for the creation of a 9mm open-bolt blowback SMG.
"The following lightweight and highly compact machine pistol design is quick to manufacture and contains a low number of components. It's minimalist layout incorporates a single receiver piece to house all components, doing away with the use of any pins or bolts to retain it's trigger grouping. These features result in a sleek and refined appearance, contrasting with the majority of weapons of this type. Constructed in it's most concealable form very little protrudes, keeping a slim profile. A design feature employed to maximize concealability is the inclusion of a single wide port on-top allowing for the bolt to be cocked without an external handle in the same manor as the US M3 Grease Gun. The standard use of 1 1/2” receiver tube and 3/4” lock collars allow for ease of lamination of internal components without using a lathe."