Feedback on gobo design wanted

These are cutaways of some gobos I'm designing for our studio. They'll be 4' (122cm) wide by 3-1/2' (107cm) tall. I'm going to sort out some way to lock them together for stacking. I'm making some which are absorptive on both sides and a few with a reflective (finished plywood) side. I'm just looking for some basic feedback. I've seen a lot of DIY designs that use Quickrock inside but at least one of those layers is playing a structural part (I would think) and so needs to be MDF, no? Would I gain anything by using a different thickness or material (say, plywood) for the second, internal layer? (I'm talking about the double-absorptive design.) And as far as putting them together, would lots of glue and a nailgun hold up or do you think I should really use some screws too?

I'm wondering what the purpose is of the air space in the middle? It seems to me that you'd be creating some sort of resonant device like that. What is the reason for that? - Stuart -

Yeah, I wondered about that, especially with the same material on both sides. I think the basic idea is cheap, light, sound-blocking. It was a theme I saw repeated in several DIY designs. For the sake of weight, (and the concern you mention) I am seriously considering reducing that to just one layer. I wish I could have found better DIY designs for gobos. These are partially based on some serious, old-school gobos that we had in one of my previous studios and online resources.

I think the basic idea is cheap, light, sound-blocking.

That's what I suspected, but that won't work. You can't block sound like that, unless the gobo is part of a structure and gets sealed into place, airtight! If it is just standing up in a room somewhere, then sound will simply wrap around it. It might block highs fairly effectively, but it will not do much for lows. Also, that air gap in the middle is pretty useless as an MSM structure, since the frame flanks it all around the edges. And in the design on the left, there isn't even any absorption in the cavity to damp the resonance! I'd just go with a more traditional design: Use the one on the right, but it split it vertically down the center of that design, and throw away the part on the left: You'll be left with something about 5 inches deep with thick plywood on one side, and 4 inches of 703 on the other side. Cover the 703 with some kind of fabric, mount the thing on wheels to make it easier to move, and you'll be fine. - Stuart -