Rubber-band-powered eye blink mechanism

First, here are some old photos of the mask framework before I added moving parts.



I figured out which parts of my face move the least: my hairline, and the bridge of my nose. The black elastic in the back has to pull the framework tight against those places to prevent the mask from slipping. If the mask is too loose, wrinkling my nose will simply move the whole mask. I sewed on a (green) piece of foam pad to keep the metal from digging into my skin.

You'll see that there is a sort of pyramid formed by 4 lines that meet in front of the tip of my nose: 2 lines from above the forehead, 2 from beside my eyes. Those two lower lines are the axes of rotation for the two main moving parts.

The two main moving parts are basically L-shaped pieces of metal. The "corner" of the L rests against the side of my nose. The "foot" of the L wraps around the axis to form a hinge. The top of the L connects to the eyelid mechanism.

These drawings are not necessarily accurate to what I ended up constructing, but they illustrate the general method.



Notice that the elastic pulls sideways. (To keep the hinge from sliding sideways along the axis, I wrapped more metal around the axis to form a barrier next to the hinge.) The elastic is anchored to a point lower than the axis, so that when my nose pushes up on the corner of the L, the elastic gets very slightly stretched. It has just enough tension to pull the L back down when I relax my nose. Too much tension would prevent my nose from pushing it at all.

Because the foot of the L is anchored to the axis, the L doesn't move in a straight line: it tries to rotate. When my nose pushes up on the corner of the L, the top of the L doesn't move straight up; it tilts away from my face. The taller the L, the more horizontal the motion.

Here's what happens at the top of the L:


The eyelid is a moving part held in place by two "hooks" that allow it to swivel. The hooks are the ends of a paper clip that has been twist-tied to a small plastic needlepoint grid, which in turn is twist-tied to the metal framework. The grids roughly cover the front edges of my temples, which is where I wanted the eyes to be placed. The twist-ties made it easy to reposition the eyelid assembly on the needlepoint grid until I found an arrangement that looked "right" before installing the L-shaped pieces.

The top of the L hooks the eyelid piece at a point close to the eyelid's center of rotation. This turns a small horizontal movement into a large rotation, so the eyelid flips over when the L tilts forward.



This is a photo of the finished left eyelid mechanism, with an attempt at a latex skin on the eyelid. The vertical part of the L piece is not a straight line; it has some angles in it, to prevent it from bumping into other parts when it moves.

It's a very finicky mechanism. I wanted to eventually put foam flesh on the mask with a layer of liquid latex skin. The problem is, the proper functioning of the mechanism relies on the overall shape of the framework. Every time I try to add something to the framework, a bit of distortion takes place. That distortion hinders the movement, so I have to make adjustments. "Adjustment" means bending the metal. And of course, if you bend a paper clip too many times, it snaps. After having to replace broken pieces several times, I got frustrated and gave up.

So there are some kinks to work out, but I think this is a good proof-of-concept. Maybe someone else, with more resources and better time management skills, can take this idea further.