I want to paint my fondant grey.. how would i do that? do they make a grey food coloring?

Do you need grey or silver? When I did a castle, I used silver lusterdust cut heavy with clear vanilla and it ended up grey, but did have a metallic finish. (go to my profile & look at the princess castle to see the color). You might have to get some spray color.

I just mix a bit of black with whitener - you don't need to use vanilla or vodka. They are both Wilton brand and you can get them at Michael's, cooking stores etc..