I have no personal experience, but I ran across these guys called Green Glue on the internet when I was researching building a soundproof box for my 3D printer because it keeps my wife up at night. They use drywall and their claims about noise suppression are impressive if true. http://www.greengluecompany.com/
I second the Homasote. I used the Homasote 440 when I remodeled my laundry room, because it was next to my TV room, and it works wonders. Cannot hear the washer or dryer through the wall - even with shoes in the dryer.
I ended up using normal drywall because I had scraps, I also glued floor mats all around on the inside, and some soundproof panels. I cover it with a heavy old blanket too. The frame is made from my old bed.
Its super good at dampening sound, I can’t even hear my machine while its cutting if I go in another room. And in the room, its quiet enough that I can forget its even on while I read or play guitar.
Totally worth building a sound enclosure imo. Also, I just put my homing switched on, why did I wait so long to do that? They’re amazing!