You can use spray paint for painting metal, I have done it but I have found that chalk finish paint works much better. (athomewiththebarkers.com)
I felt totally guilty about using spray paint on a piece of furniture until I finally worked up the nerve to try it! (worthingcourtblog.com)
Spray paint will also work; however, when using spray paint, be sure that the glass jar is placed upside down so that no paint gets inside of the jar! (happinessishomemade.net)