Oh boy, this one looks fun! My dad gave me a non functional reel to reel player as a kid, and let me take it apart. That was fun.
I also used to have one of those little sirens with microphone you could put on your bicycle when I was in Elementary school. After a few years, it broke, so I took that apart too. I found that it had a little speaker in the front. So I tore apart an old pair of headphones, used alligator clips and clipped them to the contacts, and plugged it into my walkman. Oh my gosh! Sound came out! So I hooked it back onto my bike, placed my walkman into a little bag under the seat, and had tunes while I delivered the newspapers!
Interestingly enough, like dave1490, who started this thread, not long after that, I found an old car tape deck at a garage sale for $.50, not auto reverse or anything, and was able to hook it up using a battery and the old speaker from my siren and got it to work!
Then in Middle school my aging neighbor gave me his old Panasonic SA-505 Quadrophonic receiver, turntable, and speakers. I set it up in my bedroom, and promptly put my Sony discman on it, and boombox, and had "surround" sound for several years.
-capT