This model is showing a two level reflector. This should give about double effect as one level reflector.
The corners are taken care of by dividing them into three segments. In this way more of the sunlight hits the cooker. This is more important the bigger the reflector is.
The layout is also taken into accout. Just cut it out from a sheet metal or paper and fold it together. #Solar_cooking #Solar_oven #Solar_stove