My suggestion, get a 18650 (from member AW).
IIRC it has about 2200mA of juice at 3.7v.
With a small resistor that would give you SCREAMING
lights for a long time........ ! I have 1 here in my hand and it
does not differ THAT much from a C-cell or 9v (in size).
Overall diameter is 18mm which is...
I agree, it should not project like a flashlight.
By reflector I meant some kind of reflecting dome of some sort maybe.
The Hexagonal or square shaped heatsink to which the leds would be mounted would not have to be that wide, or could even be hollow or have holes in it for cooling and would...
I like the idea, I like it very much.
However, I wonder how you are mounting the leds.
If you are mounting them all 4 (or more) on a flat horizontal surface,
do you have a reflector of some sort for reflecting the light that
would otherwise hit the "ceiling" of the lantern ?
Or have you...