You could do it as a piece of repousse work.
https://en.wikipedia.org/wiki/Repouss%C3%A9_and_chasing
I back the job with a big ball of Blu Tack, the sticky stuff for hanging pictures on the wall. Grind up and polish some bits of scrap to use as tools and tap the pattern into the surface then chase it in from behind. It works really well.
Will