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.<p>Actually assembling individual atoms together to make stuff is still very much an unsolved problem. Freitas&#x27; work on mechanosynthesis tooltips shows that we may need to control more than just position to precisely react atoms and that &#x27;fat fingers&#x27; is still very much a problem.