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Anatomical Eye Keychain

This is the story of the creation of one of my more complicated products: The Anatomical Human Eye Keychain. This example shows many of the design considerations and other issues that I commonly face when making a new piece.

This first set of images shows one of my earliest anatomy items, an eye keychain that I carved in wax. At the time I made this, I was working at the Boston Museum of Science, where there was a "frozen shadows" exhibit, which used a photosensitive material, to capture shadows which would persist after the light and the subject were removed.

For a long time, I thought it would be cool to make a new version of my eye keychain, which incorporated such a photosensitive material...

Years later, as I began to make more technically complex items, the idea reemerged, and one day, while having lunch with an engineer, I posed the concept. He immediately suggested that I simply put a hole in the back, which was a much simpler and more elegant solution than layering the retina with a photosensitive material. Eureka!

The next step was to buy lenses for prototyping... When my initial prototype yielded a blurry image, tech support at Edmund Optics helpfully explained to me that in addition to the "objective" lens, I would need an "eyepiece" lens to "re-collimate" the light.  

I carved this eye keychain long ago

Here's a screenshot of the software that I laboriously learned before discovering  it was unnecessary, and a photo of the lenses I bought for prototyping

Medial (Left), and frontal (Right) sections. Two options I considered for this piece

Next came the mechanical design phase. I considered two main design alternatives (shown on the left), a medial section, and a frontal section.


The medial section was the option I chose for my original eye, and because it cut through the optic nerve, it showed the eye's structure best, however the need for the lenses to span the two halves presented mechanical difficulties, and I ultimately decided to go with the frontal section for the new piece.

For this phase of the design, I used SolidWorks, a popular mechanical CAD software package.

Once the mechanical design was finalized, it was time to sculpt the blood vessels and other organic details onto the CAD model. For this stage, I brought the CAD model into a new software package, 3D-Coat, which is well suited to such freeform modelling.

The amount of research needed at this stage is incredible, since diagrams available on the internet are often simplified and stylized, and frequently they contradict one-another. I recall spending a long time figuring out how to arrange the vorticose (vortex) veins on the outside of the eye. The images on the right show a couple of the design alternatives I considered for the iris. 

Two design options considered for the iris

The finished product!

And that is the story of the human eye keychain. A great many details have been left out of this account, including the week spent sourcing inexpensive lenses... to loosely paraphrase a friend: "the words "inexpensive" and "lens" just don't seem to go together!

So I suppose , in fact, that this account is only about a third of the story of the human eye keychain!

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