Why wouldnt it seal? the piece of wood that holds the sub will be double baffled and wil be cut at an angle to match the top and bottom..Any reason the port piece and other non-side piece don't extend and match the angle? Don't see how that's going to seal????
Its plywood //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif cost me us $31.00 a sheet too =/x^2 on the resin. I always resin them on the inside just for that extra sureness of a good seal. And again x^2 on the outside since you are using particle board.
Box looks good though. Make sure you get us pictures of it installed and let us know how it sounds!
oh yeah, and its loud too...