If you were an alien from an advanced civilization who had been stranded on Earth, but had all your people’s knowledge on a thumb drive, how would you go about creating nanotech and building up Earth’s technology to the level you could rejoin your galactic civilization?
If you actually knew the details, probably one of the most direct pathways that’s accessible by our current technology would be to build a whole set of custom proteins that would bootstrap the molecular machinery. We can, tantalizingly, build any protein we like but we just don’t know how to design the ones that would do what we need.
This is by way of being a very verbose pointer to a very nice article at Ars Technica about some of the latest research in protein folding. Highly recommended.