I propose a new category is added under fuselages that let you choose the material. There should also be data displayed on the material and its affects. For example, density, mass, etc. It should give enough data to indicate for example if a material would be able to hold up as a heat shield, while also demonstrating the real world affects of added materials of greater mass to prevent heat damage and so on. I believe that adding this would change the ENTIRE game, and every craft created so far. This would bring a whole new real world feeling to the game and allow players to accurately create designs which will work in the real world under real life constraints and the effects of different materials. For example, the SR-72 wouldn't be able to fly with just any material for many reasons, so upon its creation its inventors were forced to work within the material constraints to ensure it can fly and resist all of natures forces.