When I was around 8 or 9, I use to borrow my dad's Phillips reel to reel and worked out that if I 'blocked' the erase head I could record on top of a previous recording without it disappearing. Very exciting to discover that. When I was older, I bought a Fostex X26 (which i still have) cassette 4-track. I hated the noise when you bounced too many times but it was invaluable training. I got an ex-BBC Ferrograph Series Seven 1/4 inch tape machine an experimented with 'varispeed' and splicing.
I've kept all the gear (outboards, mixers, machines etc) from that period and they all still work! Now, I have as much stuff as I need, although I'll probably never get over my microphone fetish.
It's incredible to think that my dad used to let me dig around in the back of valve radios to see if I could fix them. I would've been around 8 or 9 when I started doing that...and I'm still alive!