When I was 9 or so a neighbor flew a model rocked. I enjoyed it, but didn't get into it for about a year or so. For those who don't know, model rockets are commercial kits and parts. They use mostly cardboard and balsa, just like model airplanes. Like model air planes they are scale models, and are basically the real thing. Companies like Estes make and sell the parts, including solid propellant (black powder) engines with a time delay smoke/parachute ejection system. I had terrific fun with them until I started really noticing girls. I tried to get my kids into them with no joy, it must be a geek thing.