Tho X. Bui has been working with solar reflection concentrators based on the catenary curve, a curve made naturally by a hanging chain (the shape is made by gravity). He writes:
Instead of having to buy sheet metal and form it into a complex shape, then build a structure to maintain that shape rigid, the catenary reflector only require the simplest of the external frame and a piece of flexible reflecting material. Even a common sheet of plastic with one silvery side will do the job. For most of my prototypes, common aluminum foil glued to wood and cardboard does the job. For industrial, large-dimension operations, thin bright finished stainless steel sheet can do the job.
Here in our neck of the woods (Phoenix), the sun is constantly on our minds. It’s good to see a maker in the valley of the sun actually doing something useful with it! – Link.
Make a solar kitchen – Link.