I spray painted a copper coin that I sanded flat on one side. I then reverse etched off the paint with the glow forge, leaving just the skull covered with paint. I then soaked it in a 50 50 solution of muratic acid and 40 hydrogen peroxide. I then soaked it in acetone and stripped off the paint
Many years ago i made a series if silver bracelets that way. I had to do the dezign work by hand but soaked them in nitric acid. After i had done a number of them i dissolved a batch of salt and added ot to the silver nitrate that brought all the silver out of solution as silver chloride that i heated in a crucible to get a surprisingly large lump of silver that is still about somewhere.