3D printing a replica of the Helen Keller Quarter

Collecting coins without any vision has a major disadvantage: it is hard to tell what exactly is on a coin, as it is hard to feel the details. One can feel where there is writing, a head, a building, an animal, etc. But the minor details are too small for touch, which applies to most coins. When a coin is large enough, one can feel the dates, and on many coins, you can also feel the denomination.

I was always interested in the small details, and generally I used coin catalogs or sighted assistance to learn about it. But there is a way to get around it: creating a much larger copy where the details are sufficiently large to feel. This can easily be done using 3D printing.

When I added 3D design and production to my business services, you may have guessed, the first thing I got designed was a coin.

In this post I will describe the challenges and solutions of 3D printing an Alabama Quarter.

My original idea was that all you need is magnification. We created the 3D version of the Alabama Quarter in a 15 CM diameter, approximately 6 inches. And there came the surprise. The printout didn’t make much more sense. The writing was hard to recognize and the pictures were too shallow to understand. Basically, I wasn’t any further with this than the original coin.

We had to rethink the entire concept, and simplify it a bit. We simplified the writing, and made the pictures higher relief, so it would almost feel like a 2.5D representation, not really a statue, but much more than what can be seen on the coin. At this point it wasn’t necessarily an augmented replica, but it gave a better understanding of the coin.

I specifically chose the Helen Keller Quarter, because it also has braille on it, and given that I am a collector of braille coins, of which there are just over a hundred since 1981 when the first one was released by the Isle of Man, I wanted to understand what the braille feels like. My first impression was a bit disappointing. I thought if we magnified the coin, I could read the braille. But using the same magnification for the braille, the dots were squished together, practically I wasn’t able to read it. The braille actually says “Helen Keller” using English grade two braille.

Here you can see the original coin replica compared with the actual quarter. I took it to a few conferences to show, and I got the same feedback, if people figured out that there was braille on it, they couldn’t read it just by touch. After getting some feedback from blind people who are expert braille readers, it was time to take it back to the drawing board.

We found that no matter how much you magnify a coin, if you don’t understand how a picture is represented in 2D, you will need some explanation. But when the explanation is available, there is no need to make the coin replica larger. Interestingly around the time when we worked on it, I had a chance to visit an accessible exhibit of the Smithsonian where they used a similar approach, though the coin was a little bigger.

So what remained was to slightly change the braille representation which wasn’t anything like reading braille, but with braille reading experience, now it was possible to read the text.

At this point, the coin was recognizable by touch, and the braille was easy to feel.

I took this model to a few more conferences and after we made the change, it made much sense to blind people.

Generally there is much more we could do with a 3D coin, what is most important to figure out is the optimal size and the purpose of the modelling. The size will limit the amount of details that will make sense to add to the replica, and the purpose will determine which details to concentrate on. Is it for allowing a person to get a tactile representation of a coin as much as possible, is it important to be able to read the lettering or the script on the coin, is it more important to highlight a picture on the coin, etc. At this point, there is no bad approach.

For technical consideration, the coin was printed using PLA which feels like plastic but it is a degradable material. It is possible to use other materials, for example using resin we could add more of the visual details but keep the same tactile experience. Generally PLA is durable for frequent use and it is easily replaceable if needed.