STEP ONE: Using Slip, Stitch those circular halves together.
STEP TWO: Squish it a little. or a lot.
STEP THREE: Wait for the facial expression to reveal itself.
STEP FOUR: Surgically create, assemble and attach eye brows, a nose (maybe) and definitely lips.
STEP FIVE: Poke Holes for eyes. They're holes, right?
STEP SIX: Repeat Steps 1-5.