Go with MDF or super-light MDF. Fiberglass is way to expensive and hard to do and if you're not a shop is almost definately not an option. For the type of box, with that many speakers I'd go sealed since you can have a smaller airspace box. You'd have to more than double it, most likely, if you wanted to go ported. Bandpass is crap unless you're using a bandpass with ports on the plexiglass side of the box. Not as loud as ported, not as clean as sealed, and not as deep as bandpass, kind of inbetween. But for a personal built box, a nice, sealed box woudl work very well. If you can do it, invert some of the subs, it'll look ******.
If you've got pants on, you're doin' alright.
2 MA Audio dxi 12's<br />2 Excelon 401-M<br />Excelon 915 deck<br />Ma Audio door speakers