have you guys see selective laser sintering? It's a powder process that lets you print metal pieces. You can print things that would be impossible to machine (engineered voids, complex shapes) and the parts supposedly can be just as strong as a machined pieces. I'm not sure if it will spark a new industrial revolution, but I think it will change the face of industry. Just think... no more retooling costs. Making a one-off custom piece is as simple as loading a new program...and very large pieces aren't as troublesome as with a cnc mill or casting.