A small plastic sample bottle is used as the combustion chamber, and a hollow ball point pen as the barrel of the gun. A short squirt of flammable deodorant provides the fuel, and a spark from a fire lighter is the igniter.
The darts can be anything that fit snugly into the barrel, without sticking. I used the ends of ear buds as my darts.
As you can see from the video, the darts penetrate quite deeply into an apple, so please if you make one of these, please don't point it at a person or an animal.
