I liked to play some marbles when i was younger. There are seasons when we play marbles, tops, text cards, even a manually operated (we do not have a name for it) a piece of metal shaped like a hammer with a cylindrical metal at the striking end secured by rubber strips with using small black powder cakes and then we used to bang it on walls or the road usually done near or even months before the new year, a variant of it is the throw away one with chicken feathers at the top to make it land with the explosive side. Most kids now doesn't even know about it anymore. @lightsplasher
Anyway congrats to your son's graduation, here in my country the graduation is done via conference call as the normal schools are prohibited to open until the CoViD pandemic is over.
Sounds kind of dangerous. We used to make gunpowder when I was a kid. (Well, it was mostly just me.) The exact recipe was not known but I got pretty good at making things that burned up pretty well. I never packed it into anything tight to make it explode or anything though. Lots of fun. :D