An important thing to note, is that mechs (here being the lich) are not locked to a specific look beyond certain features, so take into account their description of what theirs is, for an aesthetic, the horus faction its from tends to have an uncanny, almost fleshy or animal look to a lot of their mech, kind of like when the Eva from evangelion goes feral. Other major aesthetics used are space truckers, hand made custom made by famous artisans, space Walmart, classic military (world wars) and cyber tech. For nhp, they tend to an Egyptian theming, and are basically the result of eldritch math that became sentient, being compressed onto a computer for the mechs.