The piece is rough cut parallel to the edge slightly more than 1/2 inch in from the edge, just below the centers of the holes. I chose to use a good hand held jig saw and blue painter's tape as a guide. With a plane, the rough cut is made straight and parallel to the top edge. The picture below shows the piece placed along the keyboard's front edge after planing.
The trim is glued to the front edge of the keyboard. My mentor uses good ol' duct tape to clamp the piece. My keyboard developed a slight warp after it was made, so several clamps and a spreader piece of scrap oak were used to hold it flat. Some plastic was placed under the front of the keyboard to keep things from getting stuck to the work surface. After applying glue to the back of the trim, the piece was clamped to the front edge of the keyboard. The next picture shows the clamped arrangement. (Notice at the left of the picture an experiment in using poplar to make the arcades. The wood was found to be too soft to keep from tearing out when drilled with the Forstner bits. Where have I heard that would happen?!).