Need help with maybe doing a jagged jaw head

He has a jagged jaw and I'm wanting to make a moving jaw but I'm not sure if I should make his head out of foam, or get a resin blank and modify it with a jagged jaw made of foam on top of it.

:I Kind of stumped and I kind of suck at foam work but it would give me a reason to try my hand at it again.

Any type of help would be nice. ;w;

This is Kat -hoping the image is not to big-