It is not too difficult or expensive now to find 4' or larger throwaway parabolic antenna dishes. Most come with support apparatus allowing for adjustment of position and angle. I sunk a short section of PCV pipe into the ground in which to drop the pole that came with the dish. 

I used a can of spray adhesive and silver-colored Mylar film for the reflective surface the first time, though this did not last beyond one summers use.  The next year, I used aluminum foil with pretty much the same result, deteriorating about as quickly. The next year I sprayed the surface with a can or two of aluminum paint and this reflected almost as efficiently and lasted longer than the other surfaces. I happened to have an adjustable metal trapeze stand that formally had been used next to a hospital bed which worked well as support for hanging black pots of various types.

With some attention to keeping the dish at optimal angle to the sun as it moved across the sky, I mainly use this cooker to boil away the moisture from large pots of apples which are cooked and then thickened into some great tasting apple butter. this was free energy and did not heat up the kitchen at a warm time of the year. 

It is important not to strain or damage one's eyes using this cooker, looking into the reflected sunlight on the dish.  Sunglasses definitely are recommended.   jb