This information was gleaned from http://www.williamgbecker.com/MakeSolarOven.html, retrieved 2009-Nov-15
Bill Becker's do-it-yourself solar cooker is based on the design described in Cooking with the Sun: How to Build and Use Solar Cookers. It is a box style solar cooker. The box is formed from plywood and is lined with a formed metal pan. Glazing is tempered glass. The reflector is composed of reflective film attached to thin wood and metal panels supported on plywood ribs.
Ivan's Place: Bill Becker's website