Let's say you've got a truck and need a quick way to MacGuyver a fire. has a quick and easy to convert a spare truck mirror into a fire-starting first surface solar concentrating mirror. "First surface" mirrors have their reflective coating on the outside of the glass, making them more powerful and efficient fire-starters.
The first step is to separate the mirror from the housing. Then, looking at the backside of the mirror, NightHawkInLight removes the protective paint that covers the thin metallic sheet housed inside the mirror.
With the protective paint cleaned off, you can reinstall the mirror in its housing. You'll find that the new mirror has a focal point much closer to the surface, giving it much greater heat. Be careful taking the paint off, but otherwise this is a pretty straightforward project.