Historians of machine tools, even before the numerical control era, sometimes figuratively said that machine tools were a unique class of machines because they have the ability to "reproduce themselves" [8] by copying all of their parts. Implicit in these discussions is that a human would direct the cutting processes (later planning and programming the machines), and would then assemble the parts. The same is true for RepRaps, which are another class of machines sometimes mentioned in reference to such non-autonomous "self-replication". In contrast, machines that are truly autonomously self-replicating (like biological machines) are the main subject discussed here.

von Neumann, John (1948). The Hixon Symposium. Pasadena, California. pp.1–36. {{ cite book}}: CS1 maint: location missing publisher ( link)

Merely exploiting the replicative abilities of existing cells is insufficient, because of limitations in the process of protein biosynthesis (also see the listing for RNA). Space resources: NASA has sponsored a number of design studies to develop self-replicating mechanisms to mine space resources. Most of these designs include computer-controlled machinery that copies itself.

Federation replicators often recycled waste produced by living beings – including fecal material – to provide the raw material for replicators. Such material was deconstructed down to the atomic level, and then recombined as needed into foodstuffs and other products. ( DIS: " There Is A Tide...") A more speculative, more complex microchip fabricator was specified to produce the computer and electronic systems, but the designers also said that it might prove practical to ship the chips from Earth as if they were "vitamins." Clark said that if Replicator is being put to the test, there are several things the Defense Department would need to do. Toth-Fejel, Tihamer; Robert Freitas; Matt Moses (2004-04-30). "Modeling Kinematic Cellular Automata" (PDF) . Retrieved 2007-01-04. Freitas, Robert; Merkle, Ralph (2004). "Kinematic Self-Replicating Machines - General Taxonomy of Replicators" . Retrieved 2013-06-29.Much of the design study was concerned with a simple, flexible chemical system for processing the ores, and the differences between the ratio of elements needed by the replicator, and the ratios available in lunar regolith. The element that most limited the growth rate was chlorine, needed to process regolith for aluminium. Chlorine is very rare in lunar regolith.