Has anyone out there painted/stained etc. over 6 X 6 tin tiles?

I have spryed them with a metallic rustoleom product

Paint is not very durable if it is in an area where the tiles are not hit or abraded, it could work.

Perhaps a clear Rustoleum top coat that is semi gloss or matte finish.

if you are just looking to add a dimension as in a patina, any craft paint wiped on and worked into the crevices and wiped off should do great trick.

You could and I make

my own with baking soda and a little water. See Pinterest for all sorts of recipes. I just wind it now so can’t give you specific amounts. But for this application I think I’d try paint with just a touch of water to thin it down so that it will move easy when you wipe it back. Try it with paint/Water first and if you don’t like the look, wash it off and try the chalk paint. Good luck! it will be easy tho...