I like the materials, CNC machining and one piece design but I have concern over the hop-up, I have experience that when a tight fit barrel and rubber is inserted, there maybe a chance the rubber folded, get out of place etc. For P"X"C it separate and you are able to see inside but on your design it seems difficult to check out if the hop up is in place and alignment. Secondary from the photo it is hard to see how you opened the upper part of the gear box because in my mind the hop-up must be in one piece for air tight and that means you have to find a place to separate it on the upper body. Thirdly I believe this gearbox come with quick release spring guide but a design is not good and at the same time the materials that they use was not good which broken easily. Hope your design work out good.
