100% from-scratch 445nm build

Hi folks... been awhile since I've been on here.
I finally picked up a mini lathe so I can turn my own host and heatsink on it.. I have some ambitious goals here for a somewhat large portable 445nm build. My goals are:

100% duty cycle
Water resistant
sustain nominal power output of 1W for 5 hours or more.
have the ability to select from 3 power modes, 150mW, 500mW, and 1W nominal.
Longevity.
Reed switch to control power as a safety feature- the endgame here is that the user will need to supply a magnet into a pre drilled slot in order for the main power switch to work.

I'm still in the design phase, I'm using autocad mechanical for the drafting. I'm still trying to design the electronics section including the battery housing. I'm thinking of using 6x 18650 Li-Ions arranged in a triangular shape stacked 2 units high. However I need to determine if I can power this at 1W using 3.7V input voltage, or if I need to step it up to 7.4V.

I have my eye on the FlexDrive V5, and I've read all over the forum that they can power a 445 at 1W using a single 18650 if it utilizes a heatsink. I wanted input from those that have personally used this and can attest that when heatsinked there is no worry about the longevity of the driver. I also need to know if the potentiometer on the flexdrive can be substituted for a selectable resistor array for the multi-mode power selection and if that resistance can be adjusted on the fly (i.e. with power on) without bringing harm to the diode.

To give everyone an idea of what I'm dealing with, my electronics section is cylindrical with a 1.43" diameter, 0.55" in height, with a .16" hole in the middle of one of the flat surfaces leading to the diode. The material that this cavity is bored in is Copper 110. I also have two holes drilled for the screws for the cap positioned halfway between the center hole and the outer rim, 3mm in diameter (m3 screws). If any of you would like screenshots of the design in cad to get a better picture, let me know.

I think with 1W you won't even need heatsink on the driver..
And overheating the driver won't kill it. It will lower the current, cool down a bit, then return to full power, and so on .. so the laser will start flashing.
I run V5 at 1.5A (generally its max current), with some basic heatsink .. and it overheats in 2 minutes or so.

As for pictures, sure, post some !

I can do that. Give me a couple hours, still at work. What about implementing multi mode capability? any idea if that could work?

You mean multi mode switch right ? Usually this is done by using some LED flashlight driver. Some people succeeded in it.
If you mean multimode diode, this 445nm diode which we all use works in multimode regime all the time. You can't change it.

if your idea really is 6- 18650's then a linear driver will be great. make 2 banks of 3 batts in parallel, then connect the 2 banks in series. that will give you 6000mah with 7+ volts of juice.