A long time ago I did designs like that with a sandblaster using ground Walnut shell as a medium instead of sand. For the stencil I used clear vinyl shelf paper with adhesive back.
I did some custom mirrors for bars and shopping malls. I would blast the design into the back of the mirror then spray colors into the blasted areas. From the front it looked like the design was painted then the mirror put on over that.
Big money for easy work!
You have a very smooth hand with the dremel!