Back about 1956, many of us in my Mom's Cub Scout Den earned a Merit Badge by putting together a very crude Crystal [aka "Foxhole"] Radio following Cub Scout Handbook instructions using a DIY "Capacitor", a small piece of pencil lead held by a bent safety pin, which was rubbed around a rusty razor blade until some static was heard in a very sensitive earpiece. A bent piece of metal was rubbed against a coil of enamel coated wire until the enamel was worn off along it's length...and then I could search for local AM Stations:
[My Capacitor not included.]
[Shows various versions.]
The toilet paper roll the coil was wrapped around soon collapsed, so I rewound it onto something non-metallic....and more rigid. I also tried some garnet and quartz crystals we had gathered on earlier local hikes....ahhh, much better. Later, I upgraded to a store-bought Germanium Diode (probably 1N34)...which turned it into a "real" radio, rather than a fussy Science Project.
Several months later on my 9th Birthday, my Dad rewarded my obvious inquisitiveness with a Heathkit AR-3 All Band AM Radio....which meant I had to (trial & error) learn how to solder, how radio electronics work and a bit about HF Propagation. Followed by my 4-year older brother and I working together to learn enough Morse Code to pass a (slow speed) OTA test. [After 1st year of College, I completely rebuilt the aging AR-3 from a bare copper chassis, adding RF Pre-Amp, "Wideband" IF Transformers and wood front panel that matched my DIY 12-in Speakers. [Speaker Amp had to be eliminated to make room for upgrades.]
PS: Since my Dad was a Naval Aviator [PBY, TBM, AF Hunter/Killer, S2 ASW, E1 AWACS, et.al.], he taught us how to repair cars (incl. full engine rebuild), home construction/repairs, jungle survival, et. al., although the field of electronics was new to him as well, other than radio operation as the pilot....the guys in the other seat(s) had to be much more on top of the "state-of-the-art".