Ah, DNAX, thank you....
I started a canister with 2" PVC pipe and fittings. No real magic, as you say. Some parts /info I need, please:
1. I assume a std toggle switch with a waterproof "boot". What kind of boot, where to get it and how to mount it? Other switch ideas?
2. Where to get SS side clips to hold top in place? Or, is there another method/design?
3. Built a lighthead out of 1-1/2 PVC w/ a 20W halogen MR16 - have about $7 in it so far, including bulb. Need a 1-7/8 dia lens that I plan to seal in place - any idea on material and source for lens. All so cheap and simple, if bulb goes, just dispose and throw togeher new head...unless you have good easy idea for removable lens/bulb.
4. Last question - plan to use10 NiMH "C" cells- maybe 11 for added brightness and for voltage loss in cable. This should last at least 90 minutes. Will discharge rate with 20W load overheat batts?
One objective - do all this with no power tools except a hand drill. Had to buy an NPT tap for threading for compression fittings, but that's it.
Tested the lighthead w/ 12V DC power supply. Very bright and broad coverage. Will check for narrower beam MR16. Left it on 1hr in air to test heating & heat resistance of components. Checked everything - all looks good. At hottest, I could still hold in hand - so maybe 130degF or a little more. Anyway, it works and will be much cooler underwater. The whole head is only 2-1/8 dia. and 2-1/4 long.
The biggest prob - the PVC I used is white - so definitely not "cool" looking. Maybe it will look better when it gets DIRty.
(Note - no plans to use this in extended or penetration diving - just as a bright, convenient general purpose dive light for infrequent use)