See the lovely, ancient-looking patina on the necklace and earrings shown here? It was made using using three different colors of patina inks. I used Vintaj brand, but there are a variety of different ones available. Mix them up, layer them, selectively sand them off and viola! Plain old brass or too-shiny-blah metal metal looks super old and unique. Give it a try and you'll see how fun it can be. Or just buy some of my patina-painted pieces and take my word for it :)
This necklace was made with a vintage brooch that I thought had "possibilities" but just wasn't wowing me. It was all a uniform antique-brass color. I dabbed it with quite a but of ink, even covering some of the tiniest rhinestones on it, and it made a huge difference. Then I sanded off a lot of it, which makes the effect much more convincing. I added aventurine beads and now it looks like a rare find.