is there any how to guide on how to make them or what to make them out of? cause im guessing that its alot cheeper to make them than to buy them.
Custom is pretty much limited by your imagination. Heres a couple links: http://www.the12volt.com/installbay/forum_posts.asp?TID=74519&PN=1 http://www.the12volt.com/installbay/forum_posts.asp?TID=74592&PN=1 Those should get you started.
can you just buy the sheets of fiberglass? and what is better for sound fiberglass or wood? and does giving the sub more space/bigger box than recomended a bad thing?
Yes more space than recommended can be a bad thing...Either wood or fiberglass is good for box building as long as you build it right. Fiberglass is sold in matt or cloth...The mat is stronger though.
Air resistance behind the sub acts as a spring. It helps push the coil back out and absorb some of the force. With out enough resistance and with enough power the rubber gasket(cant remember the name right now-its almost 330 AM) around the cone can tear. Now your new sub is just a $300 paper weight.
Two types of Sealed enclosures are Air Suspension and Infinite Baffle. We have an Air Suspension when the compliance of air in the enclosure is less than or equal to the compliance of the driver suspension. I think thats what wierd22person was trying to say. In an air suspension enclosure we have control of the woofer. Most Manufactures provide a range of sizes and I also recommend remainig in that size range. MDF or Medium Density Fiberboard is much easier to use than fiberglass.