Actually, you would need to take the face into a modeller; the thing you have to keep in mind about a tearing eye is that the lower eyelid acts as a catch, so what you get is a fillet of fluid that builds up on the lower eyelid -before- spilling over. That's usually how people 'know' that someone is about to cry, despite any behavior to the contrary. For it to be a prop, it would almost have to be a two part one; one part that does go over the eye, and adds the 'wet' highlights and added sheen and depth of tears, and one that parented to the lower eyelid, so that the line of built up fluid would stay with it, no matter the expression. Postwork may be easier, but if it were a genuine prop, you could map it and use textures for all sort of effects (weeping fire, anyone...?).