Easy print without supports, use FLEXIBLE material. This is a low profile universal flashlight helmet mount. It has a rail which is fastened to the bike helmet with two nylon zip ties. The flashlight holder keeps the flashlight with a firm grip, and can slide along the rail allowing the beam to come down at the desired angle.
If you have a LedLenser P7.2 flashlight, or any other flashlight with a straight body approx 29 mm, you can print and use the hexagonal holder instead. You can also scale the rail and hexagonal parts as you desire.
A hard camera or flashlight mount might punch a hole in the helmet if an accident should occur, so this thing is designed to be printed in flexible material with 1-1.2 mm shells and 20% infill to prevent that. The holder should also separate from the rail if enough force is applied. However, the safety of this thing has not been tested in any way. You decide what and how you attach extra stuff to your safety equipment, and need to consider the effects it might have to your safety.