Materials Req: A box, Metal foil, glass pane, screws and some sketching skills :P
Step I: Get a box (metallic, cardboard or wooden)
Step II: (Optional) Sketch Graphics on the exterior of that box ( so that it'll look nice)
Step III:Cover the interior of the box with metalic foil ( uniformly! )
Step IV: Get the glass pane and some screws and fit that glass pane on the top side of that box.
Step V: Use it !
Hint: You can use some mirrors to direct more sun radiation in the cooking zone :P
I'll not mind if you mark it a brainly :P