The component on the left was done largely by hand. The other two have been analysed by a computer to find the optimal design that is able to provide the same strength, but from the least amount of material. The middle component was optimised to keep the fixing points for the arms and cables in much the same place, and resulted in a 40% weight saving. The third was obtained by allowing the system to completely rejig the entire structure. It produced a 75% weight saving. [ The Economist (2015)]