Top-down manufacturing
Complementary: Bottom-up manufacturing
The prototypical example for top-down technology is the microchip manufacturing technology.
Both in case of electrical chips and in case of mechanical chips (MEMS).
With masks, optics, various ways of etching and more.
Downward size limit
Where as with bottom up the technological limit is upwards,
In the case of top down technology the technological size limit is downwards.
Reachable size-scales are less small for mechanical than for electrical chips.
While electrical chips already reach far down the nanoscale this is only possible for electrical chips and
Record holding chips are specially manufactured for chip manufacturers often at truly jaw-dropping costs.
This is nothing for quick turnaround trial and error experimentation.
Nature
There seem to be no natural targeted top down manufacturing processes.
Accidental macroscopic structure formation maybe like in sun rays melting snow in patterns and geologic processes maybe has some similarity.But these are not aiming at an encoded target structure.
Delineation
Top down positional assembly does exclude things like photo-lithography.
