We came up with 3 good possible designs, but not all of them had an arched reflective surface because to make such a surface would be relatively difficult. None of the pictures are our design but just examples of that kind of design.
First Design
The first one was a panel cooker. This would be the easiest to build design we created, but we didn't know if it would reflect enough light. Our design had 3 walls and a base which all have a reflective surface and one open side to face to the sun
Second Design
Our second design was on the lines of a box solar cooker or a solar oven. We would have had 3 walls, not as tall as the previous design's, and one panel at an angle over the top of the cooker. This cooker would be slightly harder to build considering that the angle of the top panel is critical.
Third Design
Our third design was the one that had that arched design of the reflective surface, and this would also be the hardest one to build. In our design the inside of the arch would be pointing towards the sun so we couldn't put any food down on the reflective surface itself. To get around this problem we used skewers and elevated the food off of the surface. We thought that this would be the most effective design, but also the hardest to build.