Pictured is an ultra minimal, highly compact submachine gun design which is a clear contender for the simplest ever conceived. Disassembled It consists of only nine parts including screws and springs. Almost every main component is fabricated using steel box section tube, including the one-piece thumb operated trigger.
Overall this SMG measures 15 1/2″ long and weighs a mere 3 lbs unloaded. The design has no sights and is purely a spray from the hip deal requiring the user to depress the trigger button while holding the weapon with both hands (“one hand gripping the magazine well”) to fire. A grease-gun style cut out in the bolt allows it to be cocked back “by inserting a finger through the ejection port, further eliminating protrusions such as a charging handle”. According to the designer, this weapon (the pictured prototype being a non-firing mockup dummy) can be manufactured in around two hours from under $20 worth of scrap material using not much more than a hacksaw and a drill.