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.