BCK solar cooker

http://en.wikipedia.org/wiki/Solar_cooker 

http://www.solarcookers.org/basics/how.html 

http://solarcooking.org/plans/funnel.htm http://www.wired.com/gadgets/gadgetreviews/multimedia/2008/05/gallery_survival_gadgets?slide=10&slideView=3 

 http://solarcooking.wikia.com/wiki/BCK_Solar_Cooker