NASA might rely on giant laboratories and factories to build its rocket engines, but all you need is a piece of pasta, a jar, some hydrogen peroxide, and a little yeast. Oh, and fire.
As long as you're not expecting to a put a human into orbit, this simple experiment will produce a surprisingly satisfying rocket engine on a very small scale. Mixing the hydrogen peroxide and yeast produces a steady flow of oxygen, and the pasta works well as makeshift rocket fuel. And while your creation won't produce much thrust, it still produces a decent flame, so be careful with this one.