Step 8: Paint the iris and pupil
OMG, freaky I hear you say, scary even. 1 minute ago this was half a table tennis ball, now it's a wierd eye looking up at me... ooooo, anyway, to make it look good paint a light blue acrylic circle take care to make it nice and evenly round, then when that has dried (about 5 mins) lightly paint on some white acrylic lines radiating out from the centre (makes it look like an iris), but not all the way to the edge and then lastly paint or permanent marker on the pupil. If you mess it up, you can paint over it (that's the beauty of using acrylic.
If you want perfection, then you could cut a mask from some paper and spray the eye on, but you would still need to brush on the iris features.
DON'T make the iris and pupil in the centre of the eye, Mad Eye Moody's eye was always spinning round looking everywhere but straight ahead, so make it slightly off centre.