This is a fully procedural Substance Designer + Painter material that i've made to revisit an old project (A trashy spaceship made of junk). I will make all the materials using substance. That sample sphere was rendered in Substance Painter with internal iRay engine. It's not a perfect material, and not for closeups, but it will work for use as base material for some parts.
I can change the number of metal plates and rivets interactively. I will post that material to Substance Source soon.