I have a computer controlled engraver which allows me to engrave nearly any symbol or pattern onto almost any material. It is also portable which means I can transport the machine to a home or business and engrave a design or image on someone's concrete drive or walk. Some clients request I engrave trademark logos of their favorite sports team or vehicle, etc. I'm not selling a tangible item. I don't charge any more for a popular image. I understand tattoo artists can tattoo copyrighted images on someone's skin. So what copyright issues am I facing?