The Chemical Reactor is a multi-block construction which processes fluids, most commonly hydrogen and oxygen, and creates outputs. Hydrogen and Oxygen, typically pumped in from the Electrolyser, create Rocket Fuel. The other simple recipe it can do by default is to make a large amount of bone meal per bone, 5, using a small amount of nitrogen in the process and thereby almost doubling bone meal efficiency. Use the Holo-Projector to complete the structure, then right click the Chemical Reactor machine block.
In addition to Rocket Fuel, it accepts item inputs as well, such as adding the airtight seal enchantment to armor, allowing you a basic space suit's tank and vacuum-protection abilities. Coils and Motors can be used to increase speed and efficiency.