Hot forging is a method used to form stock metal into complex shapes. For many years aluminium alloys have been the material of choice for climbing equipment as they are lighter and much easier to manipulate than comparable steels. For decades carabiners and many other products were made using a technique called cold forging, which isn't possible with steel. This essentially involves squashing 'cold' (room temperature) pieces of stock aluminium alloy with a mould, known as a die, under very large pressures until it takes the form of the mould.

Recently manufacturers have started to move towards hot forging which involves heating the alloy in a furnace before forging it. This makes it much more malleable and allows substantially more complex and subtle shapes to be moulded under higher pressures. Both of these techniques are known as drop forging, when huge a huge hammer is 'dropped' onto the material to create the pressure.

The major benefit for the end user is that equipment can be formed using the bare minimum amount of metal required, rather than using more primitive shapes, making it lighter (and in some cases stronger aswell). It also makes the application of heat treatments after the forging much easier to control, increasing consistency and, by extension, safety.