where do I get black powder? I can make it buts its sometimes unreliable
Buy fireworks (bangers are good), and extract the black powder from them.
Back in the early 70's we made a home made flash bomb for the re-launch of a club we used to help run - mixed magnesium powder with gunpowder from bangers, ran a piece of 5A fuse wire through it, and simply connected mains across the fuse wire
I made an audio tape up, starting with the theme from, "2001 A Space Odessy", the part where it builds up - then spliced in the explosion off "Dark Side Of The Moon", recorded with the VU meters bouncing off the end stops.
We assembled the 'bomb' on top of one of the speakers, played the tape and triggered it to coincide with the explosion.
Only the main DJ and myself were aware of this, I was stood the opposite side of the room, facing away, eyes closed, hands over my eyes -and everything went bright red
The silly things you do when young!.