Vehicles would still be an assembly challenge, but local parts manufacture should lower some costs and change some jobs.
It might cause more standardization (similar to the personal computer) of parts or the way they interface with other parts. OTOH it may open product design and manufacture up to thousands more budding inventors. The traditional factory may be left in the dust and may only have a chance of competing on price. May be lots more work for patent attormeys, too.

All I can think about is what this will do to drive down costs of major appliances and purchases to their true value.

Imagine a world with 3D-printed vehicles...

The great thing about additive manufacturing techniques like 3D printing is that you can put in things like stairs that you wouldn't be able to engrave away using traditional subtractive methods.