I wonder how much the change of the ability of normal people to go racing at the highest of racing has changed how we see it.
I kind of brought up in the re-invent nascar thread that of the current highest levels of the various racing- NASCAR is the only one I think that a group of GRM readers could get together and put a car together to compete with. Anything else is probably outside of our skill set to manufacture. (and I'm not talking renting an Indy car- I'm talking about making it from scratch).
Adrian has brought to light a Lotus 7 that has competed in F1, and I just read a very interesting article in a competitor magazine to CM about a guy who built a single seater with nothing more than a saw, a drill, and a gas welder. Granted, he had some experience working with lotus- so he knew how it should be laid out and designed to work. But the actual skill to make the car was VERY inside the skill set of this board.
This car competed a lot in the South African GP series, and did very well. And when it competed in an actual WC F1 race, it finished 10th- even though the tech in front of it were considerably "better". (this was a 1300CC Alfa Giulia powered car that looked much like a Cooper).
The 60's were tough for a garage builder, but once the Cosworth DFV came along, once again, it was very possible for a group of people with above average fabrication skills to put together a good F1 effort.
There are plenty of stories of Indy car homebuilts. Some of which did really well.
But over time, the change to specialized manufacturing of the chassis and aero changed a lot.
On the other hand, NASCAR is still a welded roll bar chassis with a V8- I know I'm being quite simplistic, but compared to making a modern formula car or sports prototype car- they are quite easy to make.
Exocet laser cuts tubes and welds them together as a kit for your Miata. They could easily change the program to cut and weld a modern circle track chassis.
Anyway, it's interesting to see how the top end motorsports has varied in it's accessibility for people to get into.