Hi everyone! I am a huge 3d printing enthusiast from Poland (Europe).
I run personalfactory.tumblr.com - news aggregator/blog concerning 3d printing, fablabs, open-source hardware and related.
I doubt 3D printers will become typical household appliances any time soon; if they do, they will be something like a Cricut - limited to only certain things you can print, and you have to buy or trade designs, and can only print those. Probably something a lot of people would like, but unless prices come way down on the material input costs, and quality goes way up - it will be cheaper and easier to just purchase the item, likely.
On the one hand, it would be nice to have a printer that could spit out, say, mechanical engineering parts - think a 3D printer that dumps out Lego pieces if you will. Unfortunately, there are much cheaper ways to get those kinds of parts - one off parts of such nature are much more expensive than other methods (like injection molding thousands of parts).
The main problem is that the software to design parts to print is still fairly difficult for most people to learn and use. Although I bet if you made it work something like Minecraft, and then allow some form of smoothing or other operation to make accurate parts...hmm, there's an interesting software idea.
That said - what I would most like to see is higher resolution printers. I would personally like to see a cheap, high resolution UV polymer printer come to the market (the biggest problem, though, is the fact that the UV photopolymers aren't cheap themselves).
There are some gadgets that the technophiles think are great and everybody will have one ... but it is too much for the average person. I am convinced 3D printers come in that category.
1: Even with a much simplified 3D CAD program and fully automated 3D printer there are some concepts the user has to grasp.
2: The material "plastic" is limited. Printing in metal, given forseeable technology, requires several steps and molten metal. (There is a vaccum/electronbeam metal printer possibility)
2A: Also one is limited to "single" material (mixed metal and glass print ?).
3: A printed part cost multiple times what a mass manufactured part cost. So it is only when the shops do not want to stock the item (or prohibitivly expensive) that a print makes sense.
3A: Some suggest that a neighbourhood 3Dshop will do this
If you could make almost anything, what would it be ?
Houshold items - my own cutlery and service, door handles (including the lock mechanism). If size is no limit, and material is more flexible - most of my furniture.