For this one I was commissioned to make a material generator that was capable of exporting a range of metal materials with or without paint, rust, damage, or ageing effects.

My client's goal was to have a generator that can easily export a material in a range of states that can then be blended together using vertex painting in Unreal Engine. So I opted for a parameter setup that utilised a "Time" parameter that, in combination with "Water Exposure/Rust Rate", "Damage Rate" and "Age Rate" parameters, could drive the progress of the other effects over time. The intended usage is to create the material at it's most extreme state with "Time" set to 1 and the rate parameters tweaked to the desired amount, then just export the material at different points in time. The metal/paint can even be damaged and aged without rust by setting "Water Exposure/Rust Rate" to 0.

I decided to keep it as just steel because only iron-based metals rust and steel is so common in construction, but both steel and iron looking metals can be achieved using the adjustment parameters. I also included parameters for different finishes, such as polished, brushed, sandblasted, hammered etc, and the option to enable a galvanization effect, so it's pretty versatile.

Up to 2 paint layers can also be enabled with options to set different colours and roughness values for each, or even to plug in a custom colour and/or roughness map. This is a very handy feature if there's a need to have a pattern or text on the paint layer, because rust deposits will overlap these details and doing this in post would be tough.

ArtStation Marketplace: https://www.artstation.com/a/33290918
Gumroad: https://matt-taylor.gumroad.com/l/MT_RustyPaintedSteel001