Using a pencil and a ruler, draw vertical lines down the 2-foot-square board at 2-inch intervals. Repeat along the horizontal. There should now be 144 uniform 2-inch squares drawn on the board.
Divide the 7 wooden poles into 131 pieces of varying lengths: 38 x 1 7/8 inches, 38 x 3 3/4 inches, 40 x 5 5/8 inches and 15 x 7 1/2 inches. Do this by marking the desired lengths along the pole with a pencil and then cutting along the markings using a jigsaw.
Attach the lengths of pole to the board, vertically, using wood glue. The base of each length of pole measures 2 square inches and so will fit neatly into each square on your board's grid.
Make sure not to cluster similar lengths of pole in one place as you want to create an uneven surface area. Of the 144 squares, 13 will have no length of pole attached. Similarly, make sure these 13 squares are spread evenly over the entire area of the board.
Leave the board overnight (or for a few hours) to give the glue time to dry. Paint your completed diffuser board, if you wish, to make it look more attractive, and then hang it on the wall of your studio.