https://youtu.be/zdkyGDqU7xAThis is great idea. I always wanted to figure out how to make your walls into speakers using the empty space between studs where you would put in a large box, but this is a better idea.
If they purposely made a foam or ather material for speaker you could see all speakers made like this in the future. Doesn't seem to have the compromises you make with regular speakers. I wonder how good you get the sound if you took the drivers out of really high end speakers. He is just using really cheap ones.
This is also one of the best tech youtube channels as this guy is a genius with lots of money to spend on the hobby.