Models are essential tools for understanding things that are too large, too small, or too fragile to touch.

Three-dimensional models help blind people learn about objects through touch. Manipulating a physical object engages our brains more than reading text or listening to a lecture. When sighted people can both see and touch a model, they observe and remember details of the object that the model represents.

Tactile exploration of models is important for items that people rarely have the opportunity to physically interact with in everyday life. This is particularly true for objects that cannot be touched because they are too large, too small, too fragile, or not available to touch. Here are examples of objects in each of these categories along with design considerations for creating tactile models.

The space craft in the image above is an object that most of us will never be able to touch because it is both too large and too great a distance from us. Here is what I wrote about watching the launch of the Perseverance rover that Nasa sent to Mars on July 30, 2020.

I streamed the Mars 2020 Perseverance launch on NASA TV. Just after liftoff, the broadcaster asked one of the scientists to explain the equipment that was attached to the rover. She pointed out the drilling arm on a 3D-printed replica that she was holding in view of the camera. Naturally, I wondered how the public, and especially blind people, might be able to get their hands on such a replica.

Since it was 2020, and I did not have anywhere to go at the height of the Covid-19 pandemic, I searched online for 3D-printed replicas of NASA space craft. I found a list of printable models with download links to the files designed for 3D printing. I recommend applying search filters to browse the categories of models because the site lists files for space craft, planets, and constellations. After setting up a filter for spacecraft, I found historic vehicles from the 1960s like Apollo 11 and 12, and modern rovers like Perseverance.

The models of spacecraft were designed to be 3D-printed at a significantly reduced scale when compared to the actual size of the vehicles. For example, the Perseverance Rover is three meters long. The model that the scientist held on the broadcast must have been much smaller than that. 

Buildings are another category of large objects that can be better understood by examining small scale models. People can touch part of a building, but they cannot explore the entire structure by touch. 

Tom Babinsky leads a team of designers that creates 3D-printed models of buildings. He states that a model must be small enough to handle and large enough to identify the architectural features that make the building unique.

Tom explains his design process with a description of the Empire State Building; it has 102 floors and is about 1,200 feet (365 meters) tall. If he designed a model at a scale of 1:1000, the 3D-print would be 1.2 feet (0.37 meters) tall. Each floor would be about 0.15 inches, or (0.35 millimeters) thick, and this is smaller than the width of a human finger. For this reason, Tom suggests designing a model that has the general shape of the Empire State Building instead of copying every detail of its construction.

You can read about Tom’s design process for 3D-printed models in this article.

I have described creating tactile models of objects that are too large to touch. Now I will discuss objects that are too small to touch. Tactile models of tiny objects must be produced at a scale that is much larger than their actual size.

I have written about holding a model of a DNA helix in one hand and exploring its’ spiral geometry with the fingers of my other hand. A google search reveals that “a single molecule of human DNA is only about 2.5 nanometers in diameter, which is about 50,000 times thinner than a human hair”. The model helix that I examined fits in one hand, but it is still millions of times larger than the actual DNA molecule.

Many topics in chemistry and biology involve learning about tiny objects that cannot be touched. Consider these examples.

The arrangement of subatomic particles in an atom: protons, neutrons, and electrons.

The composition of a mineral: structure of molecules in a crystal. 

The anatomy of a biological cell: its nucleus and mitochondria.

The structure of viruses: how spike proteins infect host cells.

Models can help students understand scientific concepts. When I was a teenager, one of my teachers used craft supplies to show how elements form molecules. While I do not remember the exact molecules that we studied, I can recall the elements represented as balls and the chemical bonds as sticks. Thus, each element connects to the others in the molecule.

Size is not the only quality that makes objects difficult or impossible to touch. Tactile models are crucial for safely studying objects that are too fragile to handle directly. Live animals are good examples of this category.

Recently, I participated in a tactile media workshop where we examined models of bats. Handling live bats would be unsafe because they might have bitten us, or we might have accidentally damaged their delicate wings. Models gave us a safe way to learn about bats. You can read about the tactile bat in this article from Georgia Tech where the workshop took place.

Finally, tactile models are essential when the original objects are not available to touch. The study of human anatomy is a good example because biological processes occur in our body, but these cannot be directly seen or touched. Touching and manipulating a model of the human heart enhances learning about how the organ pumps blood through the circulatory system.

Tactile models provide a direct connection to the world around us; we can explore everything from spacecraft to the human body. While sighted people use models to supplement their understanding, for blind people these tactile objects are the primary source of information. Tactile models are more than learning tools; they are essential bridges to knowledge, ensuring that everyone gains a richer, more complete understanding of objects that are otherwise inaccessible to us.