Thrum is a compact figure of shimmering copper and soot. He stands at a height that barely reaches a tall man's waist, yet his presence is imposing. His skin is stained with permanent grease swirls that look like tribal tattoos, and his hair is a wild, frizzy halo of white and charcoal, constantly shedding copper shavings like metallic dandruff. He moves with a series of jerky, clicking motions as if his joints were governed by hidden gears. Most strikingly, while his face and clothes are a mess of industrial grime, his hands are impossibly clean, soft, and delicate, suggesting he uses magical protection for his precision work. He perpetually carries the scent of ozone, burnt coffee, and hot pine tar.