6063 is often called architectural aluminum for two reasons - first, it has a surface finish that is far smoother than the
other commercially available alloys, and second, its strength is significantly less (roughly half the strength of 6061),
making it suited for applications where strength is not the foremost consideration.
6063 is rated as "Good" for forming and cold working operations, "Excellent" for anodizing, and "Fair" for machining.
6061 Aluminum is, by most any measure, the most commonly used aluminum alloy. It is specified in most any
application due to its strength, heat treatability, comparatively easy machining, and weldability. If that were not
enough, it is also capable of being anodized, adding a layer of protection for finished parts.
The main alloy ingredients of 6061 aluminum are magnesium and silicon.