Mark vertical lines down the 2'-by-2' board at 2-inch intervals, using a pencil and ruler. Repeat along the horizontal to create a grid of 144 2-inch squares.
Saw the seven wooden blocks into 131 pieces of varying length. You will need 38 section measuring 1 7/8 inches, 38 sections measuring 3 3/4 inches, 40 sections measuring 5 5/8 inches, and 15 sections measuring 7 1/2 inches. Mark the sections out in pencil, then cut along the markings using a jigsaw.
Attach the lengths of block to the board using wood glue. The blocks should be standing on end. The base of each length of block should fit neatly into a 2-inch square on the board's grid. The aim is to create an uneven surface, so do not cluster uniform lengths together: rather, disperse them about the board. 13 of the 144 squares will have no block attached. Again, make sure these empty squares are not clustered in one area. Let the glue dry.
Paint the completed diffuser, if you wish. Hang it on the wall of your studio, opposite a window if there is one. Otherwise, place it at the point where the sound from the speaker first hits the wall.
Buy a piece of rigid fiberglass. Contrary to what you might expect, "rigid" fiberglass is not rigid at all: this is simply an industry term used to differentiate it from the fluffy fiberglass used for insulation.
Cut the rigid fiberglass to your desired specifications, using a razor knife. If you have an empty picture frame, cut the fiberglass to fit inside the frame. Alternatively, you can leave the fiberglass as it is if you are not too concerned about aesthetics.
Cover the rigid fiberglass with black fabric. The fabric will not add to the absorbent qualities of the fiberglass, but it will make it look more pleasing to the eye. Hang your completed absorber on the wall of your studio.