If one is simply trying to block sound waves from traveling behind the speaker, couldn’t one simply use foam encasing behind it? Kinda of like what mix engineers use in their ‘treated rooms’ in a sound room, to absorb reflections and trap bass. Certainly one could just get some thin pieces of foam and stuff it behind the speaker and this would still allow wires to run through it not disturbing the inner guts of the saber build.
it certainly wouldn’t block the sound completely behind it, but it could at least slow down sound waves and muffle it.