Per several requests, my procedure for making wooden diffusors, similar to RPG Skylines, was as follows:
1) Purchase 2"x2" balsa wood planks from nationalbalsa.com in 3' lengths. Make sure to tell them that the planks need to be truly square in cross-section and truly 2x2 in dimension.
2) Purchase 1/4" plywood backerboard, cut it into manageable size sheets (e.g. 2'x2' or 2'x4' - too big will yield too heavy diffusors when you are ready to mount them).Get a hot glue gun (or 2) and some special hot glue sticks for wood.
3) Stain the balsa planks on their long sides.
4) See design formula at:
http://www.mhsoft.nl/DiffusorCalculator.html
NOTE: I just noticed that the link doesn't seem to be working, but I've got it captures on a spreadsheet for my particular design and there may be others out there that calculate the well depths and dimensions for an RPG diffusor. The formula specifies 5 sizes for blocks to be used to construct the diffusor. One of the sizes is zero (no block at all, just the plywood showing).
5) Get a chop saw and go into production. You will need to cut hundreds of blocks - 4 sizes total. It'll take a couple of hours, best with 2 people. Just set up a jig for the length that you want, and away you go.
6) Stain one face of each block - this will be the outside face. This will take a couple people a few hours (good to get a kid involved in this). You can also stain the outside face of your plywood backer board, or do it later once the blocks are attached.
7) Once all the stain is dry, get out your hot glue gun and start assembling the panels. This takes lots of time. I glued the blocks to the backer board, and sometimes to each other. Follow the recipe for the layout obtainable on the web (or my spreadsheet).
8) Mount them on the walls. You can place bolts with washers in the "zero wells" - that is, the wells with no blocks.
They look like are peices and they sound great! Good luck.
