Cut 2" x 4"s for messages; 1" x 4"s for bands; and 1" x 2"s for dividers. Lay the pieces out on the floor and build a pair of 2' square boxes from 1" x 4"s. Attach 2" x 4" posts to the corners and nail into place to create top risers.
Place other risers on top about 4" x 4"s to establish the same height from the floor as for the bench.
Flip the frame over and snap it into place. Make sure it's level with a carpenter's square, then secure all posts to the risers with wood screws.
Mark the location of the dividers and snap the first two into place (Image 1). Attach with the nailer, then place the remaining two on top and secure (Image 2).