Petromaton

Petromatons (from Old Basic petram, "rock", and automaton, "self-moving machine" or "droid") were any droid whose "body", or chassis, was made of a rocky material as opposed to a metal or plastic. The first humanoid automatons (historically argued to have first appeared among the Rakata and subsequently the Humans), including worker droids, servant droids, combat-capable droids, factory droids, and so on, were believed to have been made of rock (with metallic internal mechanics) and wood as these materials were cheaper to mass produce in a time where metalworking was still in a relatively primitive age. As the ability to acquire and industrialize metals progressed on Human worlds, droids made entirely of metal (known as "metalomatons") and polymers gradually replaced petromatons. By the modern era, petromatons were only produced for ceremonial purposes or in societies where metal was scarce.

Margomatons (from margarita, "pearl") were droids whose chassis was made of pearl or marble. In antiquity, margomatons were usually servant droids owned by monarchs.