Hi VV,
i'm thinking about drilling out the 35mm to fit a 12mm CU module with a full CU back and tap it for a 4-40 brass set screw that i have on hand . this way i can put in anything i want. and not be at the mercy of a press fit, if something doesn't work out..
That's a good idea, you could still attach the driver to the back. I have some 8/32 set screws and tap. May give it a try, got to order some modules. Ordering a sweet flashlight for it (I hope), holds two 18650's side by side and looks to be the right size, great for nubm44 if it fits.