Gawd, I did most of the things mentioned already. On the slingshot thing... Just after I got married, my wife worked 2nd shift as a nurse. At the other end of the apartment building lived Ed Miller. He was a jock, but had some of the same classes I did. We hiked to class together. then came the summer. The girl who lived down at the ground level had an awful dog that barked all the time. Honestly, we were just drinking a beer when the idea hit to launch an M80 out across the valley. We went out on my balcony. Ed was the launcher, me the lighter. We checked the setup and it looked good to us. But as I lit the M80, the rubber on the slingshot snapped. He did what he needed to do. Some fast footwork and the M80 was off the balcony, giving in to gravity. I think the girl was Kay (remember that was the recent one and it was 45 yeas ago) Well, her mut was outside yapping as always. Probably at us because it could hear us (its hearing was impacted, I'm sure). So the M80 it right off her little slab on the ground floor, then it went off. I was a little worried we might have hurt the dog. Ed said "so what, it was a pain". We stopped after that.
Over in the park, we launched tennis balls toward the sky. In the summer we all carried them everywhere we went, in the glove that had become an extension of our hands. So we took the clamp off the wire rope that ran through the pipes/fence posts. Firecrackers were just pop ups or infield flys. they didn't have the power to really launch them. But cherry bombs would do the job, nicely. It was how we learned to judge and catch fly balls. Better still, the pipe would muffle the sound so the locals didn't hear them and come investigating. I'm guessing the cops were never kids. They'd stop us in the week before the 4th looking for fireworks. They never even looked in the fingers of our gloves. It gave us a better appreciation of keystone cops.
A poster above suggested the fireworks in Ohio came from Kentucky. The best place over here was Bissels (might be spelled wrong). It was up in Dayton, Ky on 5th street. That was one street below 6th, or the Avenue. Nice old lady. She'd sell to kids or anyone. You could take the Dayon/Bellevue bus to the area, then walk up 5th till you saw the big B on the screen door. All the doors were the same, except some had an initial in aluminum on them. Gawd her garage was a paradise. More cool fireworks than we ever thought possible. Our other source was Tommy Groh's dad. He was a bartender down by the ballpark (Crosley Field). Those guys could get anything. I often wanted to be a bartender when I grew up.
A couple of days before the 4th, he'd call all the kids around and he'd give us a half gross of Cherry Bombs. Gawd I miss those. There must have been a machine that pressed the sawdust and glue around the flash powder interior. As I remember it, M80s had about twice the charge of a Cherry bomb, but were just about as loud. Silver salutes weren't as strong or as loud. Still better than nothing.
Times change. Somewhere, either in the basement or garage I have a golf ball cannon. It will launch a golfball maybe a half mile with enough powder. Always use enough powder! About 20 years ago I was hiking with my dog. We were on a park road minding our own business. And there, before me was a golf ball. And it had the funny but familiar discoloration. I picked it up to be sure, and one half was clean and white, like the driven snow. The other half was smoked black, just as if it had been launched by a genuine golf ball cannon! Fool the rest of the folks, I knew instantly what it was and how it got there. And my kids were in their 20s by then and the cannon was right where it should have been, untouched... I think. Just means I'm not the only fool to own one.
Did you folks know that a pipe of the right diameter inside will launch a D cell battery half way across the Ohio River? Did you also know empty coal barges run pretty much up the center of the river, in the channel? And that when a battery hits the inside of a barge, it bounces around and makes a very satisfying sound? I'm not sayin' how I know that, but...