
In 1949, Heinlein wrote this story about an entrepreneur who foresaw that future of manned space flight could not be left to governments. His protagonist, D.D. Harriman, risked his reputation, his fortune and his very life to make his dream a reality. The prescience of Heinlein's tale is embodied in a modern-day entrepreneur, who looks beyond the moon to Mars. The future of humans in space cannot be trusted to governments, whose inefficiencies would make it impossible. Though almost seventy years old, this story is more pertinent today than ever.
The solar sintering by Markus Kayser looks neet, but it is not practical in its current shape, it does not produce useful outcome. Too brittle.
The main problem is, the heat from the sun is not cohaerent.
There are fluctations in the sky for example, that will make the heat changes drastically. (there is a paper about this from a professional solar furnace, I need to find again)
Reading tip, "The man who sold the moon", from Cory Doctorow. Which also explores the idea of solar 3D sintering (but ignores the limitations).
So I do strongly believe, the whole concept has big potential, beyond entertaining SciFi - it is just not so easy. I think a way to go, could be to have the base load directly from the sun - and then a laser for the exact heat where it is need.
It should be an exciting next decade for space travel. Maybe all the sci-fi I read will start to come true. Getting anything into space is a big challenge and hopefully soon the market will have several private companies competing in a real market for space travel. For a nice short story, look up "The man who sold the moon" by Robert Heinlein. Then we can discuss whether or not Elon Musk is the re-incarnation of the fictional character DD Harriman.
http://www.amazon.com/Man-Who-Sold-Moon/dp/0671578634
(spoilers: http://en.wikipedia.org/wiki/The_Man_Who_Sold_the_Moon)
Then, for fun, go on to The Moon is a Harsh Mistress, wherein a great acronym TANSTAAFL is introduced.