Wide angle lens on home build housing

Hi Guys, I am thinking of building a simple tube housing for a HD camcorder and wondered what the best, easiest, cheapest way to attach a wide angle lens onto the front would be? The front would just be a flat perspex (or similar) disc.

Thanks in advance for any ideas.

If you buy a 67mm step up ring at the camera store, it can be attached to the front of your housing. Than any 67mm wet-mount lens can be screwed on.

Check this out: http://wetpixel.com/forums/lofiversion/index.php/t25455.html