Whats the best material to build a sub box?

plexi glass

wood....

More info on enclosures http://spkrbox1.spaces.live.com

3/4" mdx board or plywood

the industry standard is 3/4" MDF. there is a material out that is a water proof MDF, it cost about $80 for a 4x8 sheet, but it is said it can be submerged and still contain its shape...you would have to search around, and it is a special order item. A cheaper solution is to stick with standard old MDF, however to make it more rigid you could go with 7/8" or 1" MDF and also think about stiffening it with a piece down the center, about 2" all around the perimeter inside...think of the shape as like a picture frame (inside hollow) and place it smack dap in the middle of the box... also i have heard of people using wood sealer on the box before covering it, like a deck sealer... this helps make it less pourus which is said to improove sound as well (however i have my doubts). What ever you decide it is critical that the inside volume, port cross section size, and the port length are all to spec for the sub.. also use a good carpenters glue in all the seams.

You will need to know the size of box the sub requires and at what hertz the subs optimal output is for the port. If you are unsure about how to do this then it would probably be cheaper to just go buy one. A single 15" ported box is only like $35 on Ebay. You would spend close to that in just materials to build your own. You would need a 4 foot by 8 foot piece of 3/4 MDF, or medium density fiberboard, wood screws, a good sealant, and carpet. A roll of carpet is $20, the sheet of MDF will be around $30, the sealant $5, and the screws $5. not to mention you will need a skill saw, drill, jigsaw, and tape measure. Plus if you make one wrong cut, you have to go buy more wood.

i would use either 5/8" or 3/4" MDF wood and the silicone and glue dont really matter as long as they will be able to hold the box together good