[Physics] Focusing Light with Flat Mirrors

Question

What is the best way to focus (sun)light using flat mirrors? My goal is to start a fire. Cutting the mirrors is easy.

Answer 1

For an example, take a look at this guy who glued 5000 flat mirrors onto a satellite dish to "start a fire", and some more :) Ironically, it was destroyed in an unrelated fire accident later...

Solar Death ray with 5000 flat 1x1 cm mirrors

The R5800 is my latest and greatest solar creation. Made from an ordinary fiberglass satellite dish, it is covered in about 5800 3/8" (~1cm) mirror tiles. When properly aligned, it can generate a spot the size of a dime with an intensity of 5000 times normal daylight. This intensity of light is more than enough to melt steel, vaporize aluminum, boil concrete, turn dirt into lava, and obliterate any organic material in an instant. It stands at 5'9" and is 42" across. Unfortunately, the R5800 was completely destroyed in a storage shed fire on December 14, 2010.