The 'obvious' way to do that: parallel heads across the whole surface, so time is O(height). Feynman brought this up in https://people.eecs.berkeley.edu/~pister

The 'obvious' way to do that: parallel heads across the whole surface, so time is O(height). Feynman brought this up in https://people.eecs.berkeley.edu/~pister/290G/Papers/Feynman83.pdf https://people.eecs.berkeley.edu/~pister/290G/Papers/Feynman... (an 80s followup to "Plenty of Room at the Bottom"): > You should have a thicker machine with tubes and pipes that brings in chemicals. Tubes with controllable valves - all very tiny. What I want is to build in three dimensions by squirting the various substances from different holes that are electrically controlled, and by rapidly working my way back and doing layer after layer, I make a three-dimensional pattern. Added: since mechanical frequencies scale up as size scales down, this sort of design would ideally scale as O(1). That is, with smaller parts and increasing resolution, you have O(n^2) parts, each working O(n) faster, to produce O(n^3) units times O(n^-3) unit volume = O(1) volume per unit time.