Model aircraft
At age 11 I had a ‘Sleek Streek’, and successful Jetex powered Cub and MiG15 free flight models from Keil Kraft kits, then years of failed control line and rubber powered free flight. But since starting radio control in 1978 I have had a great time. I am now into waterplanes that lift off from and splash back down on the water. I have several models powered by miniature jet turbine engines that look sound and smell just like the engines in jet fighters in my youth.
I get a huge kick out of designing my own models. Most modellers, including myself, start by learning to fly a proven design that is quick and easy to build and easy to fly. But what a thrill it is to start with a big sheet of paper (alright, now a blank computer screen) and draw out my own creation, the build it from my plan and fly it. That thrill lasts for many years.