Well if you have stiff enough molecules, then the distance a given molecular structure moves due to thermal fluctuations can be smaller than an angstrom. In add

Well if you have stiff enough molecules, then the distance a given molecular structure moves due to thermal fluctuations can be smaller than an angstrom. In addition, if one cools said system down, thermal fluctuations become less of a problem. Actually assembling individual atoms together to make stuff is still very much an unsolved problem. Freitas' work on mechanosynthesis tooltips shows that we may need to control more than just position to precisely react atoms and that 'fat fingers' is still very much a problem.