Mac Series Guns
Gordon Ingram designed a series of weapons that were loosely based on the Uzi but involved simplified design and manufacture. By the mid-1960's it became evident that Uziel Gal's submachineguns were not only durable and well engineered, but they were, to a degree, overbuilt even for the rugged desert environment. The steel parts of the gun were of a grade well beyond what was necessary for the weapon to function. Cost was never much of an issue with the Israeli guns, as they were only slightly more expensive than others in production at the time. Part of the reason is that submachineguns are relatively cheap in comparison to other infantry weapons.
There was a reason for governments to seek even cheaper effective submachineguns. Clandestine operatives in the cold war wanted weapons that would be simple to use, powerful and disposable. They needed to be easy to manufacture under primitive conditions and issued to indigenous troops on a per-mission basis. In this sense, the guns were never meant to last a lifetime so they do tend to have a shorter service life than other similar weapons. .Another growing concern with covert operations planners was stealth. Successful submachineguns of the day had to be compatible with silencers and capable of quiet operation. While the Uzi was very well compatible with a silencer, the gun became much larger and heavier with the silencer attached than many covert operators were comfortable. The attachment of a silencer to the Uzi also all but mitigated any concealment advantages of the folding stock.
The MAC 10 was the gun made to order for such hush hush missions. In theory, they could be produced in clandestine shops in occupied countries or purchased in quantity by the CIA and smuggled into places where they would be used. The guns were very compact and lightweight and easily compatible with silencers. The .45 caliber chambering meant that special ammo was not necessary for quiet operation and the gun would have sufficient killing power at close range, even in the hands of an inexperienced indigenous operator. A slightly smaller and lighter version of the weapon called the MAC 11 is chambered for 9mm. An even smaller version of that gun is in .380, but in the smaller sizes, you begin to lose durability and reliability.
There are now a number of manufacturers of this weapon and parts, both commercial and clandestine. Below are thumbnails of blueprints for the basic receiver sections. The construction of these weapons, even when most of the parts are available, will require skill in precision welding the sheet metal. Construction of the receiver components requires the equipment and ability to cut and form fairly thick sheet metal, but the actual bending is almost all basic 90 degree angles.