Higher throughput of smaller machinery
When production machines are made smaller they can produce massively more product per time.
When going down the convergent assembly levels in an advanced gem gum-factory one finds that the throughput capacity of the next lower assembly stage (a monolayer that may or may conform to flat coplanar sheets) is always equal to the throughput capacity of the local stage (assuming all levels work at the same speed and throughput is balance is not influenced by other factors). The important thing is that this "monolayer" has a smaller total volume than the local stage. Going down further assembly levels one finds "monolayers" with even smaller thickness (and smaller corresponding volume) but the throughput capacity is still the same.
That is a very pleasant surprise! In first approximation halving the size of manufacturing doubles throughput capacity per volume. Going down from one meter to one micrometer (a factor of a million) the throughput capacity per volume explodes a whopping millionfold (a linear scaling law).
This can't be extended arbitrary though. Below the micrometer level some effects (discussed later) prevent further rise.
Now what if one would take many of such super thin microscale (possibly non-flat) assembly "monolayer" that one finds pretty far down the convergent assembly stack and fills a whole macroscopic volume with it.
The answer is (in case of general purpose gem-gum factories) the product couldn't be removed fast enough One hits fundamental acceleration limits even for the strongest available diamondoid meta materials and long before that likely problems with mechanical resonances.
Note that the old idea of packing a volume full with molecular assemblers wouldn't tap into that potential because these devices are below the microscale level in the nanoscale where the useful behavior of physics of raising throughput density with falling size of assembly machinery is hampered by other effects.
Antagonistic laws
The problem that emerges at the nanoscale is twofold.
- falling size => rising bearing area per volume => rising friction => lower operation speed (and frequency) to compensate – lower assembly event density in time
- falling size => rising machinery size to part size (atoms in the extreme case) – lower assembly site density in space
