Need Help with Fursuit (Moving jaw on Pony)

Hi, I didn't see anything about this on the forum, but if I've missed something then feel free to delete this. I'm new to this fandom, and new to fursuiting, so call me a noob if you wish. I'm making my ponysona Truenight, as my userpic displays. I've got the hooves done and I'm working on the legs, but this is a question about the head. I've bought balaclava and elastic because I've been wanting to make a movable jaw for her, but I'm also concerned because I've never seen a pony suit with a moving jaw. Actually I've never seen a pony suit made this way either, I know most are made from foam bases or molds.

Is it possible to make a moving jaw for a ponysuit? Or is it a bad idea? Has anyone done this before with a ponysuit, and if so, I would love to get farther help in designing, but if not, just advice on the moving jaw would be great.