Warning: In this experiment, googles and gloves were worn. Hydrochloric acid can burn skin and dissolve several substances. Make sure the bottle does not tip over.
My younger brother wanted to make a torch. He decided that hydrogen would be the easiest obtained fuel. He made a hole in the cap of a shampoo bottle and ran a hose through a valve. The hose ended in a glass pipe. He took some HCl and added it to a shampoo bottle. Then the zinc was added. The hydrogen cleared the bottle of oxygen. Then he took a heating element and ignited the hydrogen. The first try was not too good since he used too little zinc. The next try had a large, diffuse flame. In this experiment, safety procedures were observed.
He could improve it by allowing the oxygen to mix with the hydrogen in the tube before ignition. This would produce a more concentrated flame. The shampoo bottle also softened as a result of the reaction's heat. A glass bottle would be more durable.