I think 3-D printing will happen, and indeed already is happening, but I don’t see that it will bring a utopian new future. From a recent New Scientist article (gated, related version here), here are two points:
…it’s difficult to print an object in more than one or two materials…
…these combined hardware and materials issues mean that only a relatively small proportion of all people will end up printing out objects themselves. A more likely scenario is the growth of online services like Shapeways…or perhaps neighborhood print shops.
Maybe I’m blind, but I don’t yet see this as a technological game-changer. It seems more like a way of saving on transportation costs. To put it another way, what’s the huge gain of making everyone a manufacturing locavore? Perhaps there will be some new flurry of home-based innovation, based on tinkering from what these printers can drum up, but that seems to me quite speculative.