The body of the headlamp is CNC machined from aerospace aluminium alloy and anodized. It has got few advantages:
Even the best today´s LED produce some heat (approx. 40-60%). With higher luminous output, LED efficiacy decreases and generates more heat. Headtorches with maximum of 200-300 lumens cool down pretty easily, even in full or partial plastic body. Higher luminous outputs require better cooling methods, otherwise headlamp would overheat. Overheating is a problem, as its lowers LED life (LED brightness decreases over time) and electronics is more prone to failures.
When the headlamp should produce one or more thousands of lumens, proper cooling is basic prerequisite for headlamp to operate properly. The heat must be fast spread to outter aluminium body which is to the enviroment.
Two basic manufacturing processes are milling and turning. Turning is much faster but the headlamp body is limited with round shape. Thats why most chinese lamps (Magicshine) are circular. Downside of this process is that cooling ribs are oriented wrong way - they are not in the direction of air flow. So the cooling in slow speeds is limited. Ribs in the direction of air flow performs better, but cannot be made with turning. They must be cnc milled.
CNC milling takes more time but brings absolute freedom in terms of body shape and ribbing. We take this advantage in our headlamps designs, they have extreme surface size and are very efficient to cool the power which other lights cannot. Even with small size and low weight. This is the reason why our headtorches could never be cheap like chinese or plastic lights. One lamp consist of 3 cnc milled parts which are milled from 5 sides and it takes usually about 1 hour of time. But that is just net machine time, we have to clean machine, adjust, replace components and process the part - clean, sandblast and prepare for anodizing.
Last operation is anodizing which is done in anodizing fab. During this process some small 10-100 micron wide layer of aluminium oxide is developed on the outter side. This layer has got hardness of corundum and part is very durable, resistant to wear and corrosion. Part can be also coloured into variety of colors, most often its black.
Manufacturers of cheap headlamps often replace aluminium metal body with plastics. It can look very apealing and can lead customers to think its metal, even some eshops thinks its metal. You can judge it by tapping your finger on the body - aluminium is harder and produce sounds, plastic is soft and you can even bend it. The difference in use is extreme! Even today, there is still not so many full aluminium lamps.