
Here is a puppet I made using the Nice Braga pattern, which I covered with fleece. The foam for the head is a wide rectangle with arcs to bring the back of the head together. For the fleece, I used the same pattern, but added about three inches to the height of the rectangle, in order to be able to bring the mouth end of the fleece into the mouth to glue it down. That's a little extra fleece, but you can trim off the extra.
I didn't widen the fleece pattern, I made sure that the width of the rectangle was the stretchable direction of the fleece. That way I was able to avoid heavy wrinkles around the corners of the mouth.
I used 3M Super 77 spray glue to firmly attach the fleece to the foam. This also helped minimize any wrinkles.
The neck is just a tube of the same kind of fleece, with the same diameter as the opening at the bottom of the head. The tube is long enough to reach to the bottom of the body, and is hot glued to the inside of the bottom of the body.
I hope this makes some sense.
What a wonderful thing your son is trying to do. I wish him the best.