Start with a square/rectangle-ish piece of 1/4" foam.
Spray glue 2 connecting edges
Attach the top edge to the head with the corner right at the lower edge of the nose and apply the top line where you wish the top of the cheek to be. Then do the same for the bottom edge
Cut a semi circle out of the remaining side in the shape you wish the cheek to lay. Remember, if you want out more pronounced, use pie-shaped cut to make it round out more.
Spray glue the edge
add a little stuffing for shape and press the back edge down into place. Ta-da! A cheek!
Here is Norman finished. On this one, I rounded off the bottom edge of the head and attached it to the neck. He can be controlled by the normal, up-the-body manner, but I also cut a hole in the back of his neck. This allows me to sit him on my lap and control him similar to how a ventriloquist would.
I had also posted that I was making a dragon using this method. Here he is.
Just goes to show you can use this method for a wide variety of characters!
He also can be controlled both ways.