<commence trumpet blowing>
I made my first telescope when I was 13 or 14, from the famous Zeiss Jena 50/540 kit, a tube I rolled from paper and a plywood alt-az mount. That got me hooked on astronomy.
At 15 I (re-)made a Tesla coil from an old turn-of-the-century wooden base I found in the dumpster at the local uni, a 6.3kV lighting transformer, radar PA capacitors and lots of patience with the secondary coil. The thing worked beautifully and scared the living daylights out of a visitor who walked past my room and saw me drawing 15cm sparks with my finger
In 8th grade I got a popular chemistry set withdrawn from retail after I demonstrated to my chemistry teacher that the included (harmless) potassium hexacyanoferrate could be trivially transformed into potassium cyanide. I also "ran" the chemistry prep room for my teacher and set up most of her class experiments. I've blown up enough things using home made nitrated explosives to land me in Gitmo if I did it these days
Well, those were the days…
Today I'm not doing anything spectacular or particularly geeky anymore. I'm a bit of an audio nut, though, and of course love everything to do with optics.
Cheers
Steffen.