Cut three pieces of 33" x 1" x 4" and three pieces of 28" x 1" x 2". Sandwich each 1" x 2" between a 1" x 4" and a front post. For the left side, arrange flush with the outside of the left post. For the right side, arrange flush with the outside of the right post. For the middle, arrange centered against the middle post. Secure with three 5 1/2" carriage bolts through each post and runner.