For the 4th of July i was inspired to build hack a raspberry pi fireworks firing system. I quickly hacked together a node.js websocket+pi-gpio+webpage to run on the pi and quickly wired up a relay board and batteries. Check out the video down at the bottom for the first test fire!
Pi3 and 8 channel relay board switching 9v.
home made one time use starters made of electrical tape, really thin gauge wire, cannon fuse, and gunpowder