Here's my same little guy. I tried to incorporate some of the ideas you suggested in the blink project. There shouldn't be any problem nesting various colors into the iris shader. Making different shapes, though, would be tough, since the slope shader attribute is looking for parts of the sphere (eyeball) that are at an angle greater or less than the established angle. Since the eyeball is perfectly spherical, if you change the slope, the size of the blue part changes.... I don't think you would have gotten the feature-slide thing if you used the toon shader; it's a 2D animation thing, but anticipating movement is something you can do in 3D....