The metal plate is made from high-precision aviation aluminum, colored by anodizing process. Good heat dissipation, not fade and scratch-resistant. The four corners and ring are made from zinc alloy, which gets a better hardness, strong anti-corrosion and shock-resistance. Four wider and thicker corners with flannel lining to avoid scratch. The edges are processed by polishing. Four corners are polished by machine tool and electroplated by vacuum. These processes make the case with three-dimensional texture and metallic luster.