Acetylene is fun stuff!
We used mondo trash bags, inflated w/ oxy/acetylene. Taped a long lit cigarette to it at the last moment, and set them adrift across the lake (winds were favorable, of course!)
Big bad-a-boom! Shockingly big.
The other time, we filled an inverted galvanized trash can that had been pre-wired with a spark ignitor from a gas grill.
They still remember that one: “Hooooooly sh!!!!t!!” as it took off for the treetops; wasn’t much good after re-entry...
Sure. Had lots of fun with calcium carbide as a kid.