Sith ACOLYTE MASK Helmets Star Wars the Old Republic Revan props
If you type that into eBay, its the mask for 69.90. Its a vendor out of Singapore.
Its made out of urethane. I was thinking of trying to make a particle board cut of the shape of the back of the mask. Using heat to make it pliable and sticking it in there after heating it up and letting it sit for a while.
I've been suggested using a heat gun and a lot of time sitting there bending.
I'm not trying to bash the eBay seller by posting this. So please don't take it that way, they have a decent rating. But buyer beware. Look at my mask before purchasing.