I didn't use a gasket in the head pattern study. The rigid mouth plate (using a plastic folder in the prototype) and the red felt are cut the same size. The fleece is sewn inside the perimeter at bit less than 1/4 inch at the front and about 3/8 in the corners of the mouth. I would attach the throat and tongue to the red felt, sew to the fleece to the felt, glue the fleece down around the perimeter and lastly glue the felt to the mouth plate.