Eric Drexler over on Metamodern has posted a summary of "The Physical Basis of Atomically Precise Manufacturing."
Most of what he says isn't new - it comes straight from his 1992 reference/analysis work Nanosystems. Small things work faster and have higher power density. Detailed and conservative analysis shows that molecular-scale objects can be built by molecular-scale objects. (Biology is an existence proof of this last point - but the kind of machines Drexler analyzed have fundamental performance advantages over biology.)
Drexler makes an interesting point about the difference between design for easy analysis and design for easy construction, and he provides links to earlier posts of his on things like alternative materials for machine-type nanoscale manufacturing systems.
He also discusses the amount of time required for fabrication, pointing out that this is proportional to operation speed, and thus can be expected to be faster (per machine mass) in smaller machines. Perhaps in a future post he'll go into more detail on nanofactory architecture and molecular fabrication vs. component assembly. (My nanofactory paper explores these issues for a particular desing of fabricator, but it's a lengthy read and the convergent-assembly design is now probably outdated - the Burch/Drexler planar assembly design seems better in almost every way.)
Though he didn't include this observation, scaling laws also describe the huge difference between handling molecules with big machines and handling them with small machines. Not only do the small machines work faster in proportion to their size, but their volume changes drastically. People's intuition correctly tells them that a desktop machine could never build a copy out of molecules - it would take billions of billions of years. But what their intuition won't tell them is that, if you shrink the machine by a factor of a million, it should be able to build a duplicate out of molecules in a few minutes.
Even if you're familiar with molecular manufacturing, it's worth reviewing all the cool and useful things that happen at the nanoscale - which means it's worth reading Drexler's article.