3D printing is a pretty poor name. It's all additive techniques, of which there are at least six major types, I think. And they go from inexpensive hobbyist machines to over a million dollars.
They're useful technologies, but I think people are getting ahead of themselves. The focus should be on doing things that couldn't be done as well before, not making existing things, but more poorly and more expensively and thinking that's going to change the world. There are some uses though, tor example, I think GE has an turbine engine injector design that's now one piece instead of 23 pieces when done with conventional machining. In the GE case, it's a benefit, less complexity, less weight. Making a plastic tape measure with plastic tape, that looks like a waste of material & time.