There are five overarching principles for presenting and reading 3D models by touch:

1. Know what to expect
2. Gain an overview first
3. Use appropriate touch
4. Use reference points
5. Explore the detail

1. Know what to expect

Context is essential to understanding. Provide information about 3D printing, the model title, a description of the model and, if necessary, a key. 

The touch reader should be provided with a title and broad overview of the object when a 3D printed model is first presented to them. For example:

This is a model of the peak of Mount Everest. A braille label is given near the base, facing south. The model shows an area of approximately 25 kilometres along each side. Mount Everest is 8.8km above sea level; this model only shows the very top portion. 

It is also important to specify how the properties of the model differ from the real object. For example, is the real object more soft, flexible, smooth, rough, heavy or solid? Does it have a particular temperature? What is it made from? What is its scale? As always when supporting concept development, point out relationships with objects that the student already knows or that are available on hand to touch.

If it is the first time the person has handled a 3D printed object, it may be helpful to give a brief explanation of the printing process and how it affects the feel of the model. Most common 3D printers use melted plastic, which is printed in layers. This means that the base of the object will be very smooth, the sides may have small ridge lines, and any overhanging pieces may be rough on the underside where support stems have been removed or melted plastic was left dangling in mid-air.

While young children will benefit from verbal guidance from a teacher, parent or peer, accompanying text will provide older touch readers the opportunity to explore the 3D printed object independently. Consider the reader’s preferred labelling technique, i.e. verbal explanation, braille, electronic text, or interactive audio labels.

If symbols are used within the model, it is recommended that these be reproduced on a key with an associated text explanation. If the model is part of a series, it will ideally use a standard set of symbols that the touch reader can learn once and use many times. For example, maps may use standard symbols for toilets, lifts, stairs, grass, etc.

2. Gain an overview first

For any media read by touch, understanding is greatly aided by gaining an overview before examining the detail.

The first step to gaining an overview of a 3D printed model is accessing the title and description, as outlined above. The second step is a quick tactile search.

For tactile graphics, we teach students to conduct a perimeter search or the waterfall technique to gain a quick view of the whole page before beginning to read detail. These methods rely on quick sideways motion and cannot be used on 3D printed models with protruding forms that block movement.

To gain an overview of 3D models by touch, the two hands can be spread and placed carefully on the top and sides of the model. Use the palms and full length of the fingers of both hands to gain an overall understanding of the model. Smaller models can be picked up and rotated in the hand to gain an understanding of the basic shape. If the model is too large to hold or feel at once, conduct a systematic search from left to right, top to bottom or move around the model to explore it from every angle.

3. Use appropriate touch

Whereas the hand and fingers are held fairly flat to read tactile graphics, curved fingers are required for exploring 3D models. The whole hand can be used to understand the overall shape.

It is important not to have clammy or sweaty hands/fingers because they will stick and grip when you are trying to feel smoothly along a surface.

A light touch allows you to move up and over things easily without getting snagged or hurt on protruding parts.

If a student needs encouragement to tactually explore the model, then hand-over-hand or hand-under-hand techniques may be considered.

4. Use reference points

Reference points are required for orientation and when exploring detail.

It is natural to turn 3D models in your hands while exploring them. The object should be in its correct orientation when it is first presented to the touch reader. It is helpful to identify a prominent feature on the top, bottom or front of the model so that the correct orientation can be found again once the model has been turned. This should be included in the model description.

Using two hands simultaneously allows you to get an understanding of the symmetry of the object and the spatial relationship of individual parts.
To gain a better understanding of the relative dimensions, the touch reader may use a point of reference by keeping one finger on a point while tracing a line, pathway or edge. This is especially useful if the line traced goes around the object, for example from front to back.

Also it is useful to allow repeated reference of where one item/object relates to another thing before moving on to see the broader relationship to other things. It is a bit like reading braille: movement is key and the spaces and their location tells you as much about the braille character as does the presence of dots.

5. Explore the detail

Provide ample time for tactile exploration of 3D models.

When exploring a 3D model, features are first felt from the top or outside of the model. It is important to conduct a more thorough search with the fingertips to explore all of the important features. Be prepared to move inside the structure of the model, touching the sides and around the base of protruding features and feeling for holes, different levels, significant features and special markers.

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Last updated: December 11, 2021 at 5:36 am