I was about to suggest a side clickie 26650 flashlight with anodized threads, then I saw the Maxtoch D01. I also like how you made the button easy to feel even with gloves on.
Here's the thing though, I don't want the switch mounted on the driver because that makes modding more complicated. So if you're doing more side clickie lights, please do it with switches that don't mount on the driver.
Okay, here's my idea.
Battery: Single 26650 or 3x18650.
Switch: Side clickie, not mounted on driver. Big bulge around the switch so it can be easily found with thick gloves without looking at the light.
Emitter: Quad XP-G2
Optics: 24mm diameter Carclo 10624, or at least has the same dimensions for the mcpcb with optics that are readily available.
Threads: Anodized, even on extension tubes.
Battery tube: Able to accommodate protected batteries up to 71mm long. If you make it a 26650 flashlight, an extension tube to use 2x26650 would be better for some people.
Bezel: Use internal threads that can accommodate DSLR camera filters like this or this, or offer a bezel ring that can have camera filters attached. This is an inexpensive way for colored filters to be used.
Pill: Direct thermal path with a thick solid shelf for the mcpcb, and lots of space for the driver.
Tailcap and lanyard hole: Light must tail stand without the lanyard under the tailcap. This requires either two holes next to each other, or put a lanyard hole on the side like the Sky Ray King or Solarstorm K2.
No glued threads anywhere. If you want to go one step further, offer it as a host.