I remember a story a few years ago where light streams were used to redirect matter streams with relatively good precision.

The article implied this might one day lead to replicators (like those on Star Trek) where matter streams could be used to build a physical object.

Granted, the technology is in its infancy, but the fact that we are even that far along is quite amazing (considering the first airplane was built just a century ago).

There's a webpage about something kind of similar: http://www.iase.cc/optical.htm

I was thinking, perhaps it might be possible to use nano-lithography to create a nano-laser. Since light has momentum, such a laser could arrange individual atoms and molecules to perform bottom-up "opto-synthesis." Also, it could break both inter and intra-molecular bonds. For example, such a laser could take carbon dioxide and water molecules, break them up into individual atoms, then position each atom to create sugar, cellulose, diamond, a nanofactory with many such nano-lasers, and so on. Because such a device could be a semi-conductor device, it could be created using current or near-future lithography, making it easier to bootstrap MNT.