Experiment with different designs by sketching the mantel to scale on graph paper. Once you've settled on a look, use a pencil and a straightedge to draw layout lines where the trim will go. Cut the trim to size, lightly sand it, and secure the strips in place with wood glue and finishing nails. Once completed, paint the entire mantel.
Cost: About $45. Poplar panel molding, $15 for 8 feet; at lumberyards