Construction
This was made as a costume for my daughter. She said she wanted to be an eyeball. Shrugs. I cut strips cut from an old plastic barrel to define the basic sphere fixing them together with high-temperature hot glue. I removed center from a bucket-size lid to form the front of the eyeball. I covered it with sections from an old sheet, again using hot glue to hold the fabric in place.
Inside I glued a couple bats of packed-air shipping bubbles at either side of the head opening so the thing would sit comfortably on her shoulders.
Painting
I started by painting all the sheets with runny white acrylic paint. Then I mixed a dilute warm yellow and worked from the back to the front with a mouth atomizer to variate the surface a little and make it look fleshier and less like a cue ball. I went to cool blue, and then added red and worked through violet to purple red at the back. While that was still wet I used a marker to draw in some vascularity, and then I let it dry a while. I came back later with a dusting of white Krylon to even things out and tie it all together.
Details
I drew the iris and pupil on a paper plate and taped in behind the bucket lid ring. I cut a circle from some clear vinyl and attached it to the front with double-sided tape.
For the optic nerve I used a few strands of blue- and red-insulated solid-core copper wire. I twisted them around each other and around the inner structure so they would stick out sturdily.
The video is like eleven seconds long and not to loud or obnoxious and you should definitely watch it to see how the optic nerve boinged around behind her.