Black Series Vader helmet cast?

Posted in Custom Workstation

I'm trying to make a custom battle-damaged 6" Black Series Vader, and I would like to make a seperate helmet that's all broken up without damaging the regular one. I just wanted to know where I could possibly find a cast of his helmet to modify. Any help is appreciated! I'm relatively new to the customization scene, so forgive my incompetence. Thanks a ton!