Dive gear has become so commercialized that DIY diving equipment is almost frowned upon. The dive light group that lives on msn is full of design ideas and how-to’s for building some custom dive gear. My favorite is the HID cannister dive light. The light head is made from a maglite flashlight. Either a HID lamp/ballast made for ATVs or a cheap MR16 halogen is used. The batteries are contained in a seperate waterproof cannister. (Yes, I love to dive. I’ll be building some of these as soon as I buy a mini-lathe.)