The idea was that the CDs would be mounted on a hemispherical or parabolic surface, using the central holes for the mounting. A judicious tightening of the screw (and washer) where it is mounted will distort it to a focusing reflection, which can then be concentrated on a cooking device.
Consider it a Dutch Oven, but solar powered. It would probably be a good idea to have some way to monitor the heat developed, or your project may have the flavor of ashes.
Obviously, you don’t go Camping In The West. That type of solar oven/cook surface will make the rounds of BSA and LDS Ward Camp Weeks...
I’m excited...