I would say that what set me on the path (of a 3+
decade electronics career) was a Heathkit
"experimenter's kit" given to me as a present.
It had all manner of devices (actives, passives,
electromechanical, indicators) and a book of
follow-the-bouncing-ball experiment instructions.
A kid could (and did) "build" radio RX and TX,
photocell alarms, things to make noise and blink
lights etc, all without soldering (spring clips for
wires).
Kinda like a training-wheels version of what you'd
find in the various RS / Forrest Mims books, right
for a pre-teen proto-nerd.
Sort of like this one, only I remember mine being
less colorful.
im guessing these two old electronic experiment kits are from the 50s or 60s, both look to be in very good condition but im not sure if the kits are missing any pieces. in pic.1 is the science fair 15
Probably the originals are hen's teeth and priced
beyond reason (collectibles market) but if you
(say) found the docs you could build your kid
the same thing for not much money off Digi-Key
and have the corresponding experiments ready
to go. I don't know where you'd find those copper
plated coil extension springs, the board was just
masonite, nothing fancy about any of it. You
could even involve the kid in the basic construction
if you're looking to build hand/eye skills as well.