Honestly the only real working mask that wont cost you thousands of dollars is built by a guy by the name of Grusderk ( search around here and you will get the info) I will only speak from personal experience and echo a few other members. His masks are sub-par, rarely work right, and are in fact a danger to the user. Animatronic rigs have been made to work with masks, but the will cost alot of money ..are rarely self contained ( require a second, remote operator ) and may need the mask to be customized to allow for mechanics.
i just ordered my first pred head from mannowar and i've been working on a mandible system to try out in this mask, and once i get all the quirks out i'll let you know, but i can tell you, it will be simple (but effective), self contained, non-electronic, and NOT THOUSANDS OF DOLLARS FOR SOMETHING DANGEROUS AND UNRELIABLE! anyway i'll certainly put a thread up once i get the mask and start applying simple mechanics, should be awesome, as long as i can do what i'm pretty damn sure i can do with it, we'll all be in business