Large paper drinks cups are what you need for the jaw. These ones came from a fast food restaurant.
• Take one cup and draw a wavy line along it, like this. You need to draw the line so that when you cut along it, you cut the cup into two parts, with one part being slightly bigger than the other.
• Get rid of that top section.
• For the other jaw, draw a straight line along the second cup. And again, you need to position it so that when you cut along the line, one part is bigger than the other.
• Put the two jaw parts together like this, and attach them using paper fasteners.
• The paper fasteners go where you can see Fearne's third finger on this picture...
• ...like this!
• Make sure that the bottom jaw overlaps the bottom one.