Scifi. Imagine you had nano-scale robots where, given a substrate to work with, they would assemble whatever the local environment needed to look like, then assemble two child bots coming from them like twigs on the branch of a Christmas tree. This is supposed to allow arbitrarily complex construction at prices which are rounding error next to current ones, solving scarcity, reshaping the world, and generally making for a nice backdrop for your novel of choice.

[Edit: Hmm, Daniel and I seem to have different etymologies for the word...]

[Edit the second: Engrish is hard.]

They're going by the name "3-D printer" right now, but the overall idea is a home fabrication machine capable of producing complex 3-D goods (including moving parts, electronics, etc) on demand. Current 3-D printing is an extremely crude version of the eventual device.

So if you wanted a new microwave, go online and download the design. Then go to the Christmas Tree machine and have it print one up for you. Just like presents under a Christmas Tree, you ask for something, say the magic words, then it appears with a little bow on it. (It occurs to me they should have been named Santa Claus machines, but I don't make this stuff up, I simply repeat it)

Of course, we're starting off with extremely simple implementations. I think the current technology does stuff like figurines. Adding moving parts is probably a next logical step, then printable simple electronics.

There's a long way to go, but once realized, Christmas Tree machines will change everything.

I guessed 3d printer. A search results suggested it was a common science fiction term synonymous with Star Trek's replicator.