The reason the Doppelganger Automaton could appear indistinguishable from regular people was indeed due to breakthroughs in Imaginary Alchemy.
In the early development stages of the Doppelganger Automaton, before Perfikot had access to Imaginary Alchemy, she attempted to use rubber to make silicone, thereby creating "skin" similar to human tissue imitation from the original world.
However, due to the industrial level of the era and the current state of chemical development, the development of silicone did not proceed smoothly, at least not to a degree that satisfied Perfikot.
Though she did manage to create some usable materials, leading to the development of Alchemy Puppets with special customization features, those puppets were prohibitively expensive, and only the extremely wealthy were even qualified to inquire about the price.
Moreover, although the silicone material could mimic skin, its maintenance and care were not simple at all.
