This looks a lot like other DIY honeycombs I have seen. You could also make one with fewer, larger holes. The current one seems to have a lot of small holes, and is probably cutting the flash power down by a tremendous amount, and the sample photo shows how well it controls beam spread and reduces output. I think it looks like it's going to be a very useful honeycomb grid for adding just a hint of flash to areas that need only a little "kiss" of light. Overall, it looks good.
Some people have made these using sections of plastic drinking straws, contained within a rectangle made of paper or plastic, with the straws just glued into a tight "bundle" pattern inside the retaining rectangle. It seems like any number of things will work.
