The notion of a general-purpose molecular assembler or nanofactory appears to be a pure fantasy. We don't even have a theoretical approach to making that happen.
That’s not entirely true. Drexler’s books contain quite a few solutions to nanoscale engineering problems, though not for all of the problems. He designed and characterized a nanoscale mechanical system for separating CO₂ from the air, stripping the oxygen from it, then using the carbon atoms to build tiny blocks of diamond, then using the tiny diamond blocks to build macroscale objects under computer guidance.
Yes it is, but what does that have to do with my comment? It does not change anything I wrote regardless of if it was already real, is feasible but not now, will never be possible.