Black powder is asy to make. Gunpowder.
Gunpowder, also known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur (S), charcoal (C), and potassium nitrate ( saltpeter, KNO 3 ). The sulfur and charcoal act as fuels while the saltpeter is an oxidizer.
There is an excellent tutorial on powders manufacturing on Youtube. I am not joking it really is easy, and safe to make. Just be sure to follow the safety rules to the letter. You don't get a 'Do over' for screwing up.