The important point is "from as much ebay parts as possible" because I suspect there are still "jeep in a crate" boxes where all you have to do is remove the Cosmolene (this is undoubtedly not all you have to do btw)
There's a long running treasure hunt for some still-crated Spitfires that were supposedly shipped to Burma at the exact end of the war and then buried when no longer required.
The amount of equipment left over from WW2 was staggering.
This is one of those perennial aviation legends[0] that are still alive, like Amelia Earhart's wreck. Always another rich guy funding a search with promising results.
The terms of the lend lease agreement meant that Britain only had to pay for the equipment it kept after the war. So in some cases they were pushing aircraft of the deck of carriers into the sea so they didn’t have to pay for them.
Sorry, I wasn’t meaning to say that they were spitfires in particular that they pushed into the sea. I believe they were actually F4U Corsairs in that case.
You can build a Citroën 2CV from scratch with entirely new parts - almost - because someone somewhere makes what you need.
About the only mechanical component you can't buy is the gearbox "bucket", presumably because nobody ever breaks those. You can actually get various gearbox upgrades for them which is worth it if you daily one, because the mainshaft nut can slacken off and get you jammed in gear.
Unscrew the bolts holding the top of the gearbox where the selector mechanism goes, lever the main gear back into place with a long screwdriver, and then use the screwdriver to tap the mainshaft nut around until it's reasonably tight again. Then drive it home where you can fix it properly.
No, that would happen if the clutch cable snapped though. I've had this happen on a Vauxhall Astra and a VW Polo (that was actually a hydraulic pipe failing).
No biggie. Just knock it into neutral, brake to a stop, and figure out what to do after that.
Both times once I got it stopped, determined that nothing really bad was happening, and that it was safe-ish to proceed, I just put it in 1st, started it up, and went up through the gears carefully without using the now no longer disengageable clutch until I got home and could look at it properly.
A manual car is normally in gear while you're driving it. Being jammed in a gear, while catastrophic for your goal of getting to your destination, wouldn't be terrifying like an uncommanded acceleration.
If you were stuck in a certain gear you couldn't shift down to go much slower without stalling (but you can let it stall, if you were trying to stop anyway. You wouldn't be the first car to break down on the highway) and you couldn't shift up to go much faster (but in an emergency you could still floor the accelerator, wasting gas and wearing out your engine much faster).
On a slightly newer time scale there are always firearm collectors searching for something impossible to acquire now, but which might have been acquired at some point in the past and squirreled away in its factory original box in the cosmoline. Like somebody who might have purchased an imported Egyptian Maadi AKM (locally made AK47 variant) in 1982, then never unpacked it for whatever reason.
People collect these things just because, almost like pokemon cards, another example would be the rarity of finding a specific year of East German Makarov in pristine/factory new condition.
Several years ago, I bought a new in box 1981 road bike. Story from the seller was an old chicago bike shop went out of business and there were some old bikes and parts in the back. The frame is big, I'm 6 foot and I barely fit. Probably they sold the bikes with regular size frames and put this in the back, and then styles changed and they forgot about it. The brake pads wore out super quick, but everything else worked fine. I went through the tubes too, but that happens. No big collectors, so the price was reasonable as a bike to use... more than a similar used bike, but much less than a similarly nice new bike.
15 years or so ago when I was more into guns I spent a _lot_ of time on historical firearm sites looking for Martini-Henry rifles. There were still a trickle of them turning up straight from caches in Afghanistan (maybe other countries too). I never bought any because I was just a teenager, and now prices have more than doubled, of course.
And these things do exist - I know, because I have some (nascent, perhaps) - new in box LEGO sets wrapped and deep in a storage unit, spare parts still in box in the garage, etc.
Reminds me of stories where someone parks a pristine <some-car> and goes away for some reason, never to return. Then decades go by before the "barn find" is rediscovered.
The amount of equipment left over from WW2 was staggering.