Use your screw driver to disassemble the ball. Trace the paper mouth on to the plastic. It doesn't have to be perfect, but it should give you the general idea. Now use masking tape to trace the drawn line. The masking tape will ensure you a straight line. Put on you safety glasses and use the Dremel to make the hole for your head bigger (make sure you don't cut too much or you'll cut into the part that holds the bottom of the mouth). Once your head will fit through the hole, begin cutting out the mouth. Take your top half and widen the slots where you ears will go (the felt will make the birch baltic wood ears thicker). smooth out any rough spurs with sand paper. Once the mouth is cleanly cut, reinforce the other panel and mouth area with duct tape. When satisfied, reassemble the ball. Take the eyes and ears and check if everything fits perfect before moving on.