A field which 3D printing will really change is aircraft components. In conjunction with computer based topology optimisation (using simulations to find the abs

A field which 3D printing will really change is aircraft components. In conjunction with computer based topology optimisation (using simulations to find the absolute optimum 3D shape for a component), 3D printing will allow us to produce really, really light components. CNC mills are quite limited by tool paths, something which doesn't impact 3D printing at all. There's also a huge amount of potential in advanced materials. Titanium is really, really hard to machine and also very expensive (lots of wastage = lots of cost). 3D printing titanium (with lasers for sintering) is much easier (although quite slow) and can lead to very low material wastage. It probably isn't going to change an average persons living room in the next 20 years. It will change (in some cases significantly) the design of lightweight components on aircraft and other weight critical applications.