2 Push the ball inside a 2nd balloon so that the ball shows and the rest of the ball is covered with the 2nd balloon.
▶ video
3 Deflate end balloon and cut of remainder (if needed, you can leave some remainder on if you need to tie the eyes to your sculpture).
▶ video
4 And voila. You could even add more layers. I.e., the pupil, the iris, the eye white. The video shows a slightly faster method by snapping of the remainder of the balloon.