Okay, I took a break from working on the Ithorian costume so that I could rethink some approaches. In the meantime, a new tutorial came out from Stan Winston studios, the third part of a series on making a T-Rex character. It's a vehicle for demonstrating a lot of foam construction techniques, but part 3 covered making the eye. That was the inspiration I was looking for. So here's where I've gotten so far.
For this version of the eyes, I need to get a couple of clear plastic half domes. I liked the size of the 4" Styrofoam balls I used in the first attempt, even though I didn't like the material. So I cut one in half, turned a 4" disk as a base support and glued them together. Then I covered the shape in Spackle, filling all the gaps and sanded it smooth. I used that structure as a buck (the mold) in the vacuum form machine (sorry, no picture of this stage). I then pulled a form using a sheet of 0.060" styrene.
That first pull was terrible. There was a lot of webbing (folded plastic) and the texture of the Styrofoam was revealed, making the surface all bumpy. So I left the plastic on the buck, cut the webbing away, and did some sanding to try & smooth the surface. I also researched methods that other folks use to reduce webbing on vacuum forms. Using a wooden block to raise the height of the buck and a cardboard ring to force the melted styrene down around the buck, the second pull had no webbing, and the surface texture came out better. Still, I left it on the buck, sanded the surface, and pulled another form.
It took 4 pulls, each sanded smooth and left on the buck, before I was pleased with the surface and the shape. At that point I moved onto the the clear plastic form.
Here's how the clear plastic looks after the pull. The buck is elevated on the wooden platform and the cardboard ring was used to push the plastic down around the buck before applying the vacuum. These are the important steps needed to eliminate webbing on the desired part of the form..
There's a lot of plastic that needs to be cut away from the plastic dome. You can see the wooden stand is still captured in the plastic, and you can see some webbing down on the base of the plastic, well off the critical dome shape.
Next, most of the flat plastic waste is cut away using a razor cutter and scissors. What's left is the wooden stand and buck covered in the clear plastic. Then I created an ad hoc surface gauge using a craft razor and my anvil/vise in order to make an even score line on the plastic. All i needed to do was turn the buck against the razor and I got a level score on the clear plastic. Once scored, I could peel away the waste and then pop the dome off of the buck.
I'm pretty pleased with the dome shape, and so I made 2 more (one of which has a flaw and I used it for testing).
Off to Google! I needed to find a nice image of a cornea for the eye. I settled on a nice brown eye with a large pupil (but not too large). Then I used Photoshop to remove light reflections and to make a complete round image with a dark border. That was sized so that I could print it onto glossy photo paper to make a well proportioned eye.
I marked the position of the cornea onto the clear plastic and then painted some veins on the interior of the dome using the position line to limit the area. The veins will give eye a bloodshot look. Next came the tricky task of mixing up some clear polyester casting resin in order to fill the plastic dome up to the line, and then place the printed cornea onto the resin. After that dried, i painted the rest of the interior of the clear plastic dome with two colors of spray paint; a textured and speckled light brown and a solid off white. This defined the sclera of the eye.
While all of that was happening, i started to build the mechanical support for the eye. This time I decided to limit the eye movement to a side to side motion. That will make the eye movement much easier and more secure. Once again, I decided to use aluminium as the material for the structure because it's light, strong, and easy to work with. A solid ring around the eye will give a support to the movement axis and the blink pivots.
Unfortunately, I didn't get any close ups or interim shots of the bracket attached to the aluminum rings. As you can see in the above photo, I used aluminum U channel. On each end of the channel, I cut out about a half an inch of the middle, so that each side of the channel could be folded out. I drilled and tapped those "wings", and then drilled matching clearance holes on the ring. An additional strip of aluminum was cut to size with clearance holes. In the image above, you can see that screws slide through the aluminum ring, through the additional strip, and then screw into the U channel wings. All together in made a solid mount for the aluminum rings.
I placed an additional half ring on the back of the eye support rings to provide additional mounts and to strengthen the eye socket. The eye pivot shaft was cut from 8-32 threaded rod. Plastic washers provide spacing as well as a frictionless surface for the rotation. An aluminum tube was cut to size in order to provide internal support to the plastic eye. Also, a metal bracket was cut and folded to provide a lever arm (for the side to side pivot) to the back of the eyeball. Some elastic was mounted from the back of the eye socket to the sides of the eyeball support bracket. The elastic provides a return resistance to the left & right eye movement. Finally, a ball joint was added to the eyeball bracket so that a brass rod can connect both eyes, coordinating the side movement.
And here is a final shot of the pair of eyes mounted on the U channel and aluminum tube supports.