An acoustic diffusion panel is simple. It is composed of a piece of plywood with 12 rows and 12 columns of wooden blocks cut to various lengths. The plywood should be 2-foot by 2-foot. The blocks will be cut from seven 8-foot, 2-inch by 2-inch blocks resulting in a total of 131 blocks. In addition to the lumber, you will need some heavy duty adhesive and some sandpaper.
The blocks are responsible for the diffusing element of the panel. Using the eight-foot, 2-inch by 2-inches, cut the a number of blocks to the following specifications; 38 blocks that are 1 7/8 inches long, 38 blocks that are 3 3/4 inches long, 40 blocks that are 5 5/8 inches long and 15 blocks that are 7 1/2 inches long. Once the blocks are cut, sand the surfaces of them completely smooth. Use coarser sandpaper to round the corners and finer sandpapers to give them a nice smooth finish.
To complete your panel you need to glue the blocks to the plywood in a more or less random order. Begin at the top corner of the plywood and glue the blocks down flush against each other in rows. Although some plans call for a specific order, the diffusion process works just as well if you glue the blocks in random order keeping in mind a few things. First of all, you will need to place 13 blank spaces where a block would normally be glued throughout the panel. These blank spaces increase your level of diffusion and you should try to space them out so that there is one in all 12 rows with one row containing two. Try to space the fifteen 7 1/2-inch long pieces evenly as well. Another thing to keep in mind is to not fall into a pattern. Don't scatter the blocks so that there are never two blocks next to each other of the same length but also be weary of having more than two or three blocks of the same length in a row. The more uneven the surface the more effective it will be. Once all of the blocks are glued down your plywood will be completely filled. Let it sit overnight and it will be ready for use the following day.