5. BuILD pROTOTypES IN SITu Challenge: the stair’s sinuous form was tricky to execute. “With construction time so limited, we used the most common materials to build it: steel and wood,” says tsang. “it’s extremely difficult to use wood to make such organic forms.” Solution: the designers worked out the details onsite, building a fullscale mockup to finesse the finer points. “We revised the dimensions many times,” notes tsang. by using this process, 10 workers were able to erect the loopdeloop stair in a speedy five days. 44