As the title says, and I mentioned in another thread. It would be cool to be able to create air by electrolyzing water. The output of the machine would be two Hydrogen units and one Oxygen unit for every unit of water. Hydrogen could be stored and used as a fuel, and the oxygen stored and used to feed Oxygen sealers, distributors, compressors, or also stored in various tanks. Rocket fuel could be created by combining a certain amount of liquid Hydrogen (that's Hydrogen that's cooled and under pressure or in minecraft just under pressure (IE in a tank)), normal fuel (refined from oil), and a little liquid oxygen as an oxidizer.