Since moose 53 gave us a link to Will Bison's excellent, detailed explanation on the equipment and methods to make BP, I feel free to follow the example of others to tell a story or two.
My friends and I experimented feverishly in 6th grade until we developed a version of "pulverone" or the mechanically mixed ingredients known as "green" powder or "serpentine" powder. No wetting, pressing, drying and subsequent "corning". So, our BP was pretty tame, but it worked great in under water rockets we made with cardboard coat hanger tubes pinched and glued at one end. Actually they were really under-ice torpedoes which worked very well under the thin, transparent ice of a recently frozen pond.
We also found that this powder was good for making Volcanoes! My seventh grade teacher, a WWII vet who told us fascinating stories about "Fishing" in the Mediteranean with fragmentation grenades, let me bring one in when we were studying the formation of the Earth's crust. I put extra sulphur in that one for a "lava flow" effect. They had to clear two classrooms after that little caper!
I managed to clear another classroom in ninth grade with a little demo of the cannonfire possible with my version of the iron clad, Monitor. Carefully made out of cut up tin cans, it's main fearture, of course was the tuna-can turret with two music-stand-pipe cannons poking out of dual ports. Really tame flash powder using an aluminum and potassium dichromate mixture provided crowd pleasing twin billows of white smoke.
Regards,
Tracy