i someone else would recommend against the use of the term facing while there are many regional term variants i've never heard or read of this one it would be perhaps better to refer readers to the following terms where they will be able to find a lot of information engraving using small chisels gravers to carve line art into metal chasing using small blunt rods to drive particularly shaped grooves into sheetmetal repouss embossing using chasing tools and a pitch bowl to shape sheetmetal into bas relief artwork from the backside of the metal