When you can reliably print an Iphone or a tasty ham sandwich, because you are going to have to work at the molecular level to produce even a tiny fraction of what you have in you home today. A single plastic part printed is only inexpensive if you need just one. Disposable plastic silverware is WAY cheaper than you printing knives forks and spoons. I want a 3D printer, to prototype my ideas, to build small models of the large equipment I sell in my job. Those aren't household items and never will be.

The good news is that the 3D printer will help lots of little inventors design really cool and needed stuff, and help them get funding to put it in production. It will revolutionize prosthetics for injured people. I saw the Dexter robot at a trade show recently. One of the first things I thought of was "Wow they need to sell a 3D printer with every one!" Because robots are only useful when you have the right end effectors for them to work with. A 3D printer is great for that.