Well, I ordered a couple boxes of this stuff and it showed up yesterday:
PI Audio ABB1 Mr. 'T' Hemispherical Radiation: 47.5" X 23.5" X 6" - Perfect for open baffle use: Unpainted / Box of 2 pairs (M & F)
I also have some of the "Amazon slat wall stuff" sitting here that I haven't gotten to... because it's a friggin' project and I got a million of them; however, I
have found the "Bezos Boxes" make nice little test stands for the foam.

I think I'm going to give the slat wall stuff back to Jeff Bezos and will not use any of it.
I am glad I got this foam... I'm already experiencing it and it's just propped up. I really like how it's featherlight and I can move it around easily and just "rig it up and see...". The center one is balanced on an empty box... that's how lightweight this stuff is, and how unconcerned I am about it hurting anything sitting there even if it fell over. I really like that about it.
Need to be careful handling it.
There are a few ideas for how to mount it, but I think I am going to mount each piece to Coroplast (yard sign material), so it has some support, and so I am touching / handling the Coroplast instead of the foam. They are 2'x4'.
New Plan... Cake and Eat it too: - I have 8 of these, may only need 6 right now. I'm not sure I am going to mount anything permanently... we can paint / redo front wall for appearance, and I can easily place treatment in or out... it's there, it's not there... whatever / whenever.
- I may mount 2 pieces end to end to make two (2) 2'x8' tall pieces. Mounted to Coroplast and trimmed around the sides as well with Coroplast, so the foam is contained / protected back and all sides. That will easily just sit on the floor with a slight lean against the wall left and right. I can pick that up and make it all go away, upon request (which may never happen). "We will see how she likes it, and it's not permanent."
- I may mount 2 pieces in the square layout for the Center. Probably also mounted the same way as the left / right pieces, with some soft hanger (maybe made of soft foam itself) and it will just hang on the TV. That can be R&R in seconds.
So, that's the current plan... and I am real happy I went this foam route.
Why do I need 2 pieces that are 8' tall? Because there are going to be 7' tall speakers there pretty soon.

