A fire piston is an ancient device used to create embers for starting a fire. It’s usually made out of wood or metal, though in the distant past people even made them from bones. The principle behind it is adiabatic heating, where air is compressed so much and so quickly that it heats up to over 800 degrees, igniting the kindling (usually something that lights easily, like char cloth). What’s great about a fire piston is it’s essentially a lighter that never runs out of fuel and doesn’t easily break.
Whether you want to buy or make a fire piston depends on what you’re preparing for. The purpose of this site is to help people survive short-term disasters or perhaps a long, more “mild” disaster such as another great depression. In cases like that, I think you’re better off stocking up on lots of Bic lighters and strike-anywhere matches. However, recently there has been a lot of interest in making fire pistons so I’ll refer you to a great method from goingprepared. In the video below, he teaches you how to make one out of a small flashlight.