While building this dive light there will be many different choices to choose from. Here are some of the choices I have made and some that I still need to look in to.

Bulbs: HID, LED, or Halogen?
       My Choice will be LED.  They have come down in price in the last few years. They are very bright. Do not need warm up time, so the switch on and off right away. The energy efficient.

Batteries: Sealed Lead Acid (SLA) and Nickel Cadmium (NiCad) outdated by newer technologies that have no "memory" effect.  Two better options are Nickel Metal Hydride (NiMH) and Lithium Ion (Lith).
        My Choice will be NiMH. They do not require much special care. There charges are very available. I think this set with LED lights will give me plenty power for at least 2 dive or more.

Canister: PVC or PVC?
        Hmmm, PVC!