Designing a car takes a long while, there's no denying that. But even a company that's as modern as Tesla Motors still has to contend with the realities of bringing a design vision to reality. And so, to give you an idea of how long the Model 3 has been incubating at Tesla, here's a full-size clay model of the car that Tesla put into a recruitment video. In 2010.
Spotted by TheKobayashiMoron on Reddit, the basic shape of the Model 3 has been practically unchanged in the five years since. The only substantial tweaks appear to have come to the tail end of the rear side windows and the front end extending out and getting more of a "brow" point to it for the sake of aerodynamics. Of course, there's a lot of work that goes into moving from a clay model to a functioning production vehicle — a clay model of a designer's vision for the car is very different than the thousands of parts that go into an actual car.
In September 2010, when this video was posted (jump to 1:22 for the Model 3 clay model), the only vehicle Tesla was producing was the Roadster, a heavily modified electrified Lotus Elise. The Model S had been announced in 2008 and prototypes of it are seen in the video, but it was still nearly two years from the start of deliveries.