Take a sheet of 1" acrylic, mount opaque black to one side, put in our your router black side down, hog out the insides, tap mounting hole locations, cut out the letters, fill with modules (Principal/Sloan prism nanos), and install on a folded backer. Sure, you can install all these on the wall, but they you'll have to fish all the wire up to the ceiling and tie it together. With a panel, you can have the customer get an electrician to pull a circuit to the location.