You don’t come across as knowing much about 3D printing (or the design work that goes on before the printer starts up), or assembling the parts you’ve designed and printed, or about carbon-fiber layup, or about mating all of that with the metal parts needed to make a car body into an actual car.
Actually, yes I have an idea. And due to the article (not general title of “building it with 3D”), yes, I know there would be mating it with other parts and many involved processes - esp. since it’s doubtful there would be a very large vat for private hobbyists to use.
In my day, it was called rapid prototype.
But it’s not quite the same as working metal or even fiberglass and putting all THAT together.
But yeah, the reality is much more involved than the simplistic title suggests.
BTW - design work: scanning in blueprints or even parts of a well-known car and transferring it to CAD. Yes, tweaking will have to go on as “technology” is never perfect, but basically all that design has been done by some Italians already.
And again, this is a very topical comment; not opining on the actual details. It’s a glib assessment.