> Robert's essay was very interesting and enlightening. I haven't
> seen this kind of detailed analysis before. But 5 years to build a
> Gates-style mansion? I had no idea it would take so long.
It won't. There is no point in building massive structures from reactive moieties atom-by-deposited-atom (unless one is a perfectionist nano-aesthete wanting to live in a perfect-crystal diamond mansion the size of the Ritz). We can rather mine carbonates/soil carbon/air carbon dioxide, turn them into few-atom polymerizable precursors a la simulated photosynthesis and cobble them together quickly a la tightly controlled polymerization/convergent (auto) assembly. Sapphire is a very very exclusive substrate indeed.
Working with silicates deposited from aqueous solutions could also be worthwhile.
This also illustrates very well why monkeys are not going to make it. Too space/time/energy inefficient. Also, too dumb/slow to protect themselves.