Being a printer, I have thought about this a lot. I'd do an overlay but if you do make sure you use a hardcoat polyester or polycarbonate. We stock this at my shop for printing control panels, membrane switches and graphic overlays. It will resist scratches longer. I have made vinyl overlays for playfields, but the hardcoat materials look like glass. Do you have art yet? I could print you a test overlay. The other issue with polyester or polycarbonate is the cutting. It's difficult to cut with xacto or razor blades. I have a punch set I use for round areas and some hack job steel rule dies for switches. I bet you could use a Dremel as well.