The sun switch can be built from readily available scrap electronic parts. You can build the Sun Switch to fit any solar cooking oven. Common ABS plastic (plumbing) can be used to build the device but it can also be easily made from wood or metal. The basic principle uses a shadow vane (simply a piece of plastic) which cast a shadow over the sensor LEDs. When the earth rotates the sensor LEDs are slowly exposed to the sun as the shadow tracks east (opposite the direction of the sun). The exposed LEDs produce a voltage which drives a simple circuits attached to a motor. The circuit can track the sun very accurately.
The sun switch uses very little energy and can be powered by a small solar panel of a few watts. You can view sun switch plans (a version made for a PV panel solar tracker) on my website  in the solar tracker section. Please feel free to edit this page and add details of any sun switches you build.