Nice work there rayjay, I like your take on the collection cup, a little different than the conventional setup around the outside of the reaction chamber. Since you've resurrected this thread, it might be a good time to present a few photos of my DIY basswood air stones.
Here's my first attempt after being in use for many months (lost track but it was still working quite well). I put a rock inside before assembly to weigh it down.
Assembly of the new one, in service now. Since the basswood plank I have is relatively thin, I need to fuse two sections together for each of the four sides to get a good sized diffuser out of the deal
As you can see here, I don't use precision tools, just a hand saw & miter box, so I don't always get an even cut. A bit of sanding takes care of that and it's really not that critical due to the large surface area you get from the box design
And the new one, ready to go. Not quite as clunky at the top & bottom as my first effort and I used basswood for the ends, whereas with the first one I just used some pine I had laying around. I find there's a bit of a break in period with these DIY diffusers and they actually get better with age, to a point...
