Cardboard price increase is inevitable, but we could alleviate the cost impact per solar cooker if we are able to reduce the amount of construction material needed in making each solar cooker. In early 2008, Teong Tan set a goal to create a functional solar cooker, from a flat sheet of cardboard, by using 25% less material than that required for a CooKit solar cooker. The end result, after about eight month's time, is the Sunny Cooker.