This is one of my boxes covered in fleece awaiting the first application of resin. The box's dimensions are: Length 18" Base W 9.5" Top W 4" Height 12.5" This gives the boxes approximately .83 ft? after sub displacement. The back, sides, top, bottom and speaker ring of each box is made from ?" MDF. the speaker ring is mounted at a parallel angle to the slope of the box, slightly raised to enable me to give the box some shape.
Here you see the boxes after a couple applications of resin. I first gave the fleece a resin "skin" or thin layer on top, just thick enough to make it sturdy. Too much resin on the first application and you can make the fleece sag. (next time I'm using t-shirt material) I then poured resin on the inside of the box to allow the fleece to soak up as much resin as possible and seal any potential cracks. I then used several layes of fiberglass mat (not the woven stuff) to add strength.
In this pic you can see the boxes after MUCH sanding and you can see the hole I cut to install the terminal cups. Some people don't like using terminal cups because of the possibility of loosing some pressure from a bad seal. I find the convenience of being able to quickly remove the boxes if need be much more valuable. This is not a competition system, though I do compete, I'm just not trying to break any records with this;)
A note on easy removal though, if it's easy to remove for you, it's easy for a theif to remove also. So you will have to weigh the pros and cons of such an implementation for yourself. In my case, my system is hidden for the most part and I live, work, and go to college in fairly safe enviroments.
Here the boxes have been sanded down and I have primired one to get an idea of how they would look painted, and to help highlight any imperfections I might have missed in my sanding. In the end, I decided that I wanted to cover them in vinyl.
Here are the boxes all stitched up in vinyl. I had them done for about $45 at a local shop. As I mentioned earlier, upholstery is one of the few things I have no desire to try my hand at.