UPDATE:
The box is built, looks pretty good, I’ll probably post some picks once i get the carpet on.
A tip for anyone planning on building a box...Acoustiseal is brutal, i would not use it again. I decided I would give it a try when i saw it at the home depot, BIG mistake. First off, its absolutely brutal to work with, makes a huge mess. There is a reason they say use it only in concealed areas. Second, once i got the inside seam all covered, before setting up the space heater to make sure I don’t burn down the house, I read that acoustiseal DOES NOT DRY, so far its only gotten tacky...stick with a silicone based caulk, I wish I did, still waiting to decide whether i should try to get the acoustiseal out, or just stick with it.....