I'm a fan of the HD2010 running 2 x 26650 batteries. I'm not sure what driver you would run but with your machining and as according to OL anodizing abilities the sky's your limit. If you machine up a new pill for a larger driver and without any more effort a new battery tube altogether your not limited so much with the 17mm driver. Heres a picture of a one made earlier.
On my pill I had to machine the inside diameter of the battery tube to fit over the outside of the driver when the tube was screwed into the body, Iike this. https://budgetlightforum.com/t/-/9637?page=1#comment-215270
Looking forward to seeing what you come up with.