Above is an experiment I did using the rust sample below with a grey coloured version to see if I couldn't make some realistic weather-worn bolts. They stand out in stark contrast to the shiny brushed aluminium underneath.
Whenever I find a design or image that I like, I see if I can find a image big enough to use as a wallpaper without losing any of the integrity of the image. These are a few I have created using guides and visuals that are the intellectual property of someone else. I'm just borrowing them.