Something shiny for a change! I passed by a tarnished brass doorknob earlier and decided to recreate the material. I took a photo used Artomatix to mutate it into a tiling 2K greyscale texture, which I used to derive the textures for the PBR material. I tested the material in 3DSMax 2020.2, the improved material and lighting display in the viewports makes it super easy now. Some images were rendered in Toolbag.
Material - Tarnished Brass