I have discussed the possibility of 3-D printing of solid objects before, in this article where company #5, Desktop Factory, is detailed. However, the Desktop Factory product can only produce objects that have a maximum size of 5 X 5 X 5 inches, and it can only use one type of material.
On the Next Big Future blog, the author quite frequently profiles a future product capable of 'printing' entire buildings. This technology, known as 'Contour Crafting', can supposedly construct buildings at greater than 10 times the speed, yet at just one-fifth the cost of traditional construction processes. It is claimed that the first commercial machines will be available in 2008 itself.
Despite my general optimism, this particular machine does not pass my 'too good to be true' test, at least before 2020. A machine that could construct homes and commercial buildings at such a speed and cost would cause an unprecedented economic disruption across the world. There would be a steep but brief depression, as existing real estate loses 90% or more of its value, followed by a huge boom as home ownership becomes affordable to several times as many people as today. I don't think that we are on the brink of such a revolution.
For me to be convinced, I would have to see :
1) Articles on this device in mainstream publications like The Economist, BusinessWeek, MIT Technology Review, or Popular Mechanics.
2) The ability to at least print simple constructs like concrete perimeter walls or sidewalks at a rate and cost several times superior to current methods. Only then can more complex structures be on the horizon.
I will revisit this technology if either of these two conditions is solidly met.