Start by cutting the wall molding to the desired size. Using a miter saw, cut four pieces of wood into two equal sizes (this will make one design), making sure the ends are cut at a 45-degree angle.
Decide where you want the molding placed on the wall and measure out the designs to make sure each rectangle will be evenly spaced and symmetrical. Then, using a level and a pencil, mark the walls so that you have a guide when attaching the molding.
Next, attach the side pieces (Image 1). Apply wood glue to the molding. Line up the mitered corners (Image 2) and follow the marked guidelines. Attach to the wall by pressing and secure with nails (Images 3 and 4). Repeat this step for the rest of the rectangle (Image 5).
Once all four pieces of molding have been attached to the wall, let the wood glue dry for about 2 hours.