This is a process for using glue gun glue for eyeball muscles (I believe it was Cassie7's eyeball muscles made from liquid latex that gave me the idea). I'm not wanting to take credit for anyone's creativity...
I got some cheap and decent foam eyeballs from Michaels (posted in the Eye-rises flower thread I just made). 4 eyeballs for $1, not as good as homemade, but good enough for what I work with. The fact that they are foam means you can cut into/melt them so that works even better than the pingpong balls for this project.
I had a large crow/raven from Michaels as well. I wanted the raven to have a fresh eyeball dangling from its beak, so using the foam eyeball, some glue gun glue and red and black paint...
I used the glue gun to trail out lines of glue like the eye muscle would be, but went over the area a few times so as to get a more organic effect. I used a ceramic plate for this so as to make the glue once cooled easy to peel up. I actually wet it down with some cool water and stuck the whole thing in the freezer for a few minutes, and they peeled right off.
Once I had the glue muscles the way I wanted, I peeled them off the plate, used a bit of red and mostly black to paint the whole thing. Let that dry, went back over it with a half red half black so it was a deep red color, but only on the high points and sort of tracing the main lines down the muscle. When that dried, then straight red as a very fine tracing over the highest points.
I used the glue gun to melt into the foam eyeball slightly (the general depth/width of the wide part of the muscle where it would attach) and then glued the muscles into/onto the eyeball. I had to hold it in place as it dried, but I didn't get any of the hot glue on me as I used a VERY small amount. I then took the two muscles and pinched them together and applied a small amount of glue at the juncture to make them meet, and there was a nice skinny section at the top that I inserted and then glued into a small hole in the beak (cut in carefully with Xacto knife).
I did a small tail of glue on the opposite side of the beak to look as if the raven was holding the muscle.
I did some minor touch-up painting with red on the new glue bits and over the back of the eyeball to get the reds to match a bit more, then coated the entire muscle/eyeball with polyurethane to get it REALLY glistening. The cool part is that with the eye hanging with the pupil straight down, the excess polyurethane formed a cornea effect at the bottom... happy accident, but it looks so real.
The eyeball also swings easily with the slightest movement.
I'm naming him Edgar.