Unless you are a beginner or creating a stylized production, your character’s eyes should be made from a material other than clay. If your figure is made of clay, the eyes should stand out from the rest of the face. If you are using a plastic or latex mold, your eyes should have a realistic appearance if only to blend in with the lifelike look of your puppet’s head.
The easiest materials to use would be ready-made glass or plastic eyes. These can be purchased at hobby or craft supply stores, and are usually labeled dolls eyes. If you decide to use these eyes for your characters, try and find ones that are completely round orbs, as opposed to flat, static shapes. If you use the round balls, you will be able to insert them directly into your puppet’s head and tilt the iris different ways in order to mimic realistic movement of the eye.
Another great tip is to consider browsing internet websites that sell taxidermy supplies. The eyes available from these companies can be relatively inexpensive, are multi-dimensional, and work very well when shooting close-up camera angles because they contain details such as color-tints and tiny blood vessels.
If you are constructing a fairly delicate puppet, or do not want to have to move the eye around in its socket, use white glass balls to simulate the shape of the eye, and then put clear petroleum jelly on the surface of the ball. Place a small circular paper on the jelly to represent the iris, and then simply slide the iris across the jelly with a toothpick to create motion for your animation.
A trick used with great success in the Wallace and Gromit films is to use white beads with depressions drilled into the front center portion