Built a subwoofer box!
I used dimensions I got off the internet to get a 1.25 cubic foot internal volume. It's super boomy and awful right now but that's because it leaks from every seam because I have yet to caulk it. I have no idea how I'm going to use a caulk gun through a 12" sub hole, but that will be interesting. Also that handle is a piece of accessory belt from an old Chevy Blazer.