An important design aspect is the type of metal used to build the body weight support system. Aluminium and steel were both considered. The team chose to go with aluminum because aluminum has a yield strength of 35,000 psi, more than enough to support the user, and because of its resistant to corrosion when compared to steel. This will allow for better machining of the body weight support system. The resistance to corrosion helps the device from deterioration due and sweat produced by the patient or the humidity in the air. Alloy 6061 T6 is generally used as the most versatile of the aluminum alloys and will allow the team to better machine, weld, or extrude if needed.