I have been watching 3D printing technology for a while. If you are not aware, a 3D printer uses plastic, resin or another medium and 'sculpts' for lack of a better term, items from scratch. It is not new technology, as manufacturers have been using 3D printers for quite a while to produce molds or mock-ups for new items prior to production runs.
The technology allows you to create a 3D image of an item on a computer then have that item produced in real life rather then just a picture of it, on paper. What is absolutely amazing is that these machines are starting to pop up everywhere. They used to be tens of thousands of dollars and only produced plastic replica's of items to give a designer a feel for what the end product would look like. Now you can buy a makerbot thingomatic kit one for a grand. The bike on the right was entirely produced by a 3D printer.
Recently a group of college students created a printer / robot mash-up. It produced its own Lego pieces, then stacked them to build a house. It could build any house you asked for, based on a picture you chose. From resin goop to house instantly. The new super expensive ones can use multiple types of raw materials and combine them, or change color or texture as needed, based on the design. Sure they are expensive now - but so were computers.
Fast forward another 20 years and these things will be as common in a house as laptops or iPods are now. Need a new dog bowl - just print one, how about that new superman action figure - poof here you go.
What will be really intersting is when we get to the point of using a 3d printer to create a 3d printer....