I used a new product that CSUSA is selling now. It's called "Modern Masters Metal Effects Aging Solutions. (say that real fast, ten times!) Here is the link
https://www.woodturnerscatalog.com/p/51/6413/Modern-Masters-Metal-Effects-Aging-Solution?term=patina
So here's the deal. I haven't tried using the paint. I just wrap a tube in copper and then just spray a little of the Green Pantina, let it dry, hit it with some of the brown color and then hit it with some of the blue pantina. It takes about 15-30 minutes to dry. It's great fun and you can get all kinds of patterns! There is an iron base paint that you can buy with it, but it's not needed if you're using real copper wrapped around your chosen pen tube.
Give it a try. It's a lot of fun!