The material used on the fiberglass campers is called filon. It’s fairly thin though not exactly cheap. You can apply it to a surface with adhesives like epoxy. Want something cheap and durable? HDPE or ABS plastic sheet. Use a router or dremel to cut your outline and a heatgun to form it. Rubber-like? Visit a truckstop and get one of the big mudflaps. Use a handsaw to cut it to size. 3M makes a helicopter blade tape that’s abrasion resistant. It’s an excellent tape to put where rocks are thrown or in high use areas that are painted.