When I was making this plague mask, I wanted to make it look unique. Instead of going for the normal black mask I originally made it gold. I wanted to make it look like it belonged to someone rich, but then I started messing around with the texture so now it looks like copper or bronze. I liked this look a lot more so I added some scratches to make it look like it had been used quite a lot.
Here I made a new material and used "1+Left click" to create values for the metal and roughness. I used "3+Left click" to add a colour. I used "t+Left click" to add a normal map. I then created a material instance to make separate variations of this material.
This is a goofy character named John Orb that I made to apply the textures to.
Texture atlases can be used for 2D objects in 3D games. It can be a sheet with several objects on it that you can isolate and use. For example, if you have a field of grass, instead of modeling each blade of grass individually, you can just put an image of grass from the texture atlas on a 2D plane. This is a lot more optimized for games and also probably more time efficient. It also reduces the draw call.