You guys are totally ignoring the progress of every technology in history if you do not think 3D printing will be common place one day. Not soon for all the reasons mentioned, but it will be common place eventually. A century or two from now everyone will make their own stuff because no one will be able to compete with the cost of the massive manufacturing of the commodity of a block of metal. Assuming the world does not fall apart from all our current social problems, something I am not optimistic about.
People said some of the same things about desktop publishing and 2D printing. Printing at home? But that requires knowing how to use a computer, that would never happen. Who does not have a printer now?
With current technology it is interesting if limited. Within the limitations, if I need to make something I can download it, press the mouse button 5 times and my printer makes it. Why are people going on about 3D printing being incredibly complex for the end user?
BTW, I envy all you machinists. Although I think it inevitable that 3D printing will change manufacturing radically one day, we and the next generation will be long dead by then and getting into 3D printing has created an interest in manufacturing in me. Traditional machining is where it is at right now, and I wish I knew 1/50th about it as much as you guys do, let alone 50/50th. :-)