Cutting lenses for eyes

The construction and assembly of colored eyes for the 2019 Maratus volans head.


Jurgen Otto's famous photo of a Maratus volans in full mating display on a blade of grass. The eyes are metallic green, set in on a head of alternating orangered and grey stripes, with white-haired pedipalps.
This photo by Jurgen Otto shows the details of the Maratus volans face. Note the shape of the pedipalps and the coloration of the eyes.

Eyes are perhaps the most materially difficult part of any costume, especially when you want to be able to see through the eyes. Note the metallic green sheen of the eye surface in the above photo.

In 2018, I bought a pair of oversized dark-brown sunglasses and cut up the lenses to make the eyes. It was adequate, yet nowhere near as accurate as I’d like.

The 2018 head, which has eyes as dark brown-black circles in a plush grey face.
The 2018 head.

So for 2019, I aimed for something much more ambitious.

A foreshortened view of the 2019 head, with eyes inserted. They're not green; they're a pale metallic blue.
This is the final end product of the 2019 eye-creation process. Note the metallic sheen as well as the apparent translucence.

Shaping the lenses

Early in the process of building the 2018 skull, I popped over to the local Ace (the helpful place!) Hardware to ask what ideas they had about making the eyes. I got a cast-off sheet of 1/8th-inch plexiglass, and started experimenting with what would be necessary to shape it as needed.

Over the course of shaping the eyes, I used the following tools to cut and trim the plexiglass:

For bending the plexiglass, I used an electric toaster oven heated to about 375F/190C, a 2” glass sphere paperweight, and a metal jar lid. I hammered the center of the lid out some so it was further from the rim, so that the plexiglass had more space to move when being pressed onto the sphere by the lid’s rim.

You will need:

My complete shaping process was:

  1. Trace circles onto the protective film on the plexiglass.
  2. Cut the circles out with a fine-toothed coping saw. Cut carefully so that the cut shape is as close to the desired final shape as possible. The saw is the easiest way to shape the plexiglass. Do this in a place with adequate ventilation and air filtration, as the fumes emitted by hot plexiglass are unpleasant. The sawdust clings more than wood sawdust.
    You’ll also want to do the sawing with the plexiglass supported. If you’re cutting on the edge of a table or bench, keep the saw blade as close to the bench edge as safely possible, to avoid putting stresses on the plexiglass that may cause it to snap.
  3. Place the cut-out plexiglass circle atop the glass sphere, with the metal jar lid on top of the plexiglass. It may help to think of the lid and sphere as a hammer and anvil, or opposite sides of a press. The jar lid’s rim presses around the edge of the plexiglass circle, while the sphere presses in the center.
  4. Put the sphere-plexiglass-lid stack in the toaster oven, and heat to about 375F/190C.
  5. Watch the plexiglass carefully for signs of bubbling. Boiling the plexiglass will make it very difficult to see through. If you see bubbles, pull the stack from the oven to let it cool a bit while you reduce the heat in the oven a bit.
  6. When you pull the stack from the oven, press down on the jar lid, thereby pressing the softened plexiglass down onto the glass sphere. If necessary, remove the jar lid and further press the plexiglass onto the sphere with protected hands.
  7. If necessary, repeat steps 3-6 until the plexiglass is adequately curved.
  8. If necessary, trim the plexiglass while it’s hot with tin snips or metal shears. You’ll want to use a tool that gives you good leverage and is manipulable by your gloved hands. And unless you’re keeping the shears in the oven with the plexiglass, your shears will be cooler than the plexiglass, and will suck the heat from the plexiglass quickly. This isn’t a bad thing, but it’s why I didn’t use the shears for big cuts: the plexiglass isn’t easily cut when it’s colder than about 300F/150C.
  9. When the plexiglass has cooled, finish off any rough edges with a rasp or file meant for hard materials. I have a lovely metal file, normally used for sharpening axes, which was adequate for this purpose. You will probably want work gloves for this step. If the plexiglass shrieks upon the file, you’ll want earplugs to help protect your hearing.

Repeat steps 1-9 above as necessary, until you have enough lenses. For the two small eyes, four medium eyes, and two large eyes of this Maratus volans head, I cut about 5 large lenses, five medium lenses, and three small eyes. I lost two of the larger lenses to bubbling.

The next step in the process is to color the lenses. I haven’t written that up yet, so this is it for now.