Alright, I will be sticking with a sealed one any to start since it takes up less space too. I looked it up and here is what I will have to build for my sub maybe minus the black carpet:
5/8" MDF (medium-density fiberboard) with black carpet covering •internal volume: 0.76 cubic feet •dimensions: 14-1/8"W x 13-7/16"H x 11-5/8"D1 x 8-1/2"D2
Shouldn't be too hard,