A few years ago, I made a headlamp based on this instructable: https://www.instructables.com/id/Ultimate-Night-Vision-Headlamp---500%2B-lumens-with-/
There are numerous instructables that detail the building of a headlamp utilizing a computer heat sink and big ol' high wattage LED's. The downfall of all of these, in my opinion, has been that building a helmet mount has proven tricky. In fact, I was so frustrated by the helmet mount situation that, after multiple different iterations of a complex contraption involving screws, string, and custom eyelets, I decided to go to a bike store and see if they had a helmet mounted lighting system I could buy ready made. They rebuffed me and told me the best lights they've seen were home made and sent me back home to keep designing. This is the second time Bike n Hike has told me not to buy one of their wares. Well, the other day, I had an epiphany. Rather than explain it, I think it better to just show you a picture of my solution. The O-ring is just a standard type found at a hardware store.