Scan the coin surface with a micro‑CT or confocal microscope to get a height map of every scratch. Export that as a 16‑bit grayscale height map. Convert it to a normal map so the GPU can simulate the light‑falling on those micro‑irregularities. When you UV‑unwrap the sculpture, map the height map to the UV so each tiny groove is represented in the texture. Use a PBR workflow; set roughness to match the patina, and add a small bump offset in the shader to give that extra play of light. If the data set is huge, bake LOD levels so the high‑detail map only shows up close. That’s the core; tweak the shader’s specular to mimic bronze’s old‑world sheen.

Keep the shader in two parts: a reusable material function for the bronze base, and a small wrapper that plugs the height map in. In the function, calculate Fresnel with a fixed roughness, and drive specular intensity from the normal map. Use a single set of texture coordinates for all passes so you don’t have to duplicate code. Don’t inline everything—keep the main passes minimal, call the function from each. Test with a reference plate; if it looks off, adjust the specular scale once and it will apply everywhere. That keeps the code tidy and the sheen consistent.