I've spent the past weekend getting my shader network up for the Trim sheet. I thought about doing it with Functions, but this approach with regular material attributes is fine. When I finish this scene, I'll probably go back and use functions to make the shader network. For the layers, I have Grunge, Paint, and Rust. I'll need to punch up the contrast between the vertex colors and getting the base metal underneath to show...not sure how I'm tripping up on that.