As you read this think about the fact that this was written in 2012 so that many things now are 3d printed than you think

Additive manufacturing is not yet good enough to make a car or an iPhone, but it is already being used to make specialist parts for cars and customised covers for iPhones. Although it is still a relatively young technology, most people probably already own something that was made with the help of a 3D printer. It might be a pair of shoes, printed in solid form as a design prototype before being produced in bulk. It could be a hearing aid, individually tailored to the shape of the user's ear. Or it could be a piece of jewellery, cast from a mould made by a 3D printer or produced directly using a growing number of printable materials.
But additive manufacturing is only one of a number of breakthroughs leading to the factory of the future, and conventional production equipment is becoming smarter and more flexible, too.
end partial quote from:

1. "A third industrial revolution". The Economist. 2012-04-21. Retrieved 2016-01-04.
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3. By the way people HAVE USED 3d printers to build the bodies of cars in pieces since this was written. They just bought 3D printers big enough to build a plastic or fiberglass type of body with it.Also there are also 3D printers big enough to build a home especially with cement all over now.