1. Solar Panel out of Aluminum Cans (by Malden P) This design most closely resembles the commercial product sold by Cansolair. The site has very good pictures and step by step details to build a full-size passive solar heater. Rating: Excellent Design. Definitely worth a look - 7 DIY Pop Can Solar Heaters
DIY Solar Water Heater From Plastic Bottles - Make a solar water heater from a pile of plastic bottles and cartons. This is great for the environment as it frees up waste trash and if you decide to build one you could use old bottles or what ever you have available.