What the-! How'd you do that?! That whole room just- just- just built itself!
—Harry Trinskade observing Programmable Matter being activated
Programmable Matter was a Progenitor and Progenitor Human technology and science designed and built for hundreds of millennia for the purpose of an easy-assembly, easy-disassembly material usable to create any given design they could feasibly program it to create. Originally, during the years of the United League in the Cradle before and in the beginning of the War of the Ancients, Programmable Matter was relatively rare. It was expensive and complex to create, and thus, it was not ready for large-scale deployment to aid the war effort in all its theorized applications, ranging from medical treatments to weapons assembly to fortification construction. However, in time it became progressively easier to create and program, smaller and smaller in size, leading to the eventual situation in which much of Progenitor construction was in fact built via the conversion of energy directly into additional Programmable Matter which would then assemble and solidify itself into whatever form they might need at a given time.
By the time of the Galactic Republic's founding, Programmable Matter was an uncommon but fairly well-known technology within the Ethereal Demesnes and seemed poised to become a chief Progenitor export to the rest of the Demesnes and, in time, to the greater galaxy. However, a variety of factors prevented this so strongly that it still had barely spread through even the Demesnes by the time of the Clone Wars. The three most prominent of these were thus; Firstly, the technology was difficult to translate to non-Progenitor use, as Progenitors and Progenitor Humans used not only a different alphabet and language, unique to their society, but also a different set of numbers, a different form of mathematics itself, and even a unique coding language, a variation of trinary coding in which code would be layered on top of itself, accessed in three dimensions rather than two dimensions via a screen. Secondly, the Progenitor and Demesnes governments agreed to limit the technology's export for self-defense reasons, preventing the greater galaxy from using it against them on any significant scale. Thirdly, with request and support of the various Senatorial delegations of the Demesnes, the Republic Senate agreed to ban any non-government approved import of the technology from the Demesnes, though this law was considered archaic and irrelevant by the time of the Invasion of Naboo.
In fact, Programmable Matter had advanced such by the time of the rise of the Galactic Empire, its Progenitor creators had found ways to program it to externally alter itself to such a degree that it would become indistinguishable from "normal" matter. This worked so well that visitors to their space were regularly startled, fascinated or confused by how they could, seemingly, create entire new buildings in minutes simply by bringing in sufficient Programmable Matter and coding it as needed. However, it was not always used for such a benign purpose; oftentimes, it was used as a means to rapidly assemble reliable weapons, armor and vehicles, albeit it was virtually never used for starship construction on the basis of, according to Arkos Tavarakous, "its potential to be destabilized and thus kill everyone aboard". This concern did stop the Progenitors from constructing some starship, satellite and space station weapons emplacements using Programmable Matter, however.