RDNA has some great materials in their free stuff area. Everything from metal to fabric and brick.  To use them just go to the material room, pick the part of the object you want to apply the material too and double click the icon in the library. The material is applied. No fuss or muss.  They did the hard work :)

Of course that doesn't mean you can tweak things once you are familiar with the material room. But usually when it comes to metals you don't have to do much tweaking if it's a good set of materials, which the RDNA ones are.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi