This fantastically huge housing was put together by [Ed Sauer]. He put together this housing using TIG welded 6061 aluminum for the body and machined the port mount out of 7075 aluminum. The lens port is a commercial unit from a housing manufacturer along with a few manual controls. He wrote up the build in this pdf.
http://www.hackaday.com/2008/06/27/mega-underwater-diy-video-housing/