Build a backpacking stove out of two aluminum cans: design is strong, reliable, and extrordinarily lightweight, burns alcohol fuels, and can be made for next to no investment of money. Boil water rapidly, deploy a 'campfire' in the middle of your house, and amuse yourself, with a stove that weighs ten grams and costs nothing.
Step 1: Assemble Your Parts
You're going to need:
Two empty aluminum cans and one full one. The type matters very little, although there are some bottom-brand beer cans that are simply too thin to make a good stove; this assumes a 12 oz can although obviously the 14 oz tall cans work since I'm using one.
A single edged razor blade
Some number of thumbtacks and a nail
A piece of flue tape (ideal) or heavy gauge aluminum foil
A ruler, book, and sharpie marker
Your life will be made easier by a hammer and a pair of scissors