Tactile Problem/Solution Bank Project

Contributed by
Ultimaker in partnership with MatterHackers

3D modeling and printing should be accessible to every educator because 3D printed models provide an affordable alternative to purely visual images, offering  students a tactile means to understand spatial and other concepts.

Whether it is the creation of models and manipulatives, the conversion of 2D images to 3D tactile objects, or the ability to place Braille on designed objects, 3D printing allows teachers, and specifically teachers of the visually impaired, to have personalized learning aids that empower them to improve the learning experiences of their students.

This community project started with designing tactile models for the visually impaired, but it is also about using design to ensure that teachers have access to educational materials that are accessible regardless of learning styles, physical, or sensory abilities. So if you're not sure that your model is 100% appropriate for a visually impaired student, we still encourage you to submit your solutions if you believe they can help other students understand a concept, lesson or idea.

The Tactile Problem/Solution Bank project is evolving aims to address the following topics:

  • Education — To learn about the best practices for designing tactile objects for the visually impaired.

  • Submission — To provide a way for teachers of the visually impaired to share their needs for specific models and for models that help explain specific ideas.

    Request a model by submitting it to the Requesting a model from the Tactile Problem/Solution Bank.

  • Application — To apply those best practices to design so that  visually impaired students and others can explore specific ideas.
  • Share — To publish, share created models on Youmagine.com, to tag them with  #tactileSolution, and  to link to it from Benetech's ImageShare.

This page will be a living document. As resources are created and best practices are refined, this page will continue to update.

This project will be ongoing.

Requested ModelsActivitiesBest PracticesTactile Graphics StandardsResourcesSoftwareInspiration

Requested Models

Model or ConceptAge group Other information
Imperial to metric volume translation for recipes outside of US.High SchoolEncourage international recipe exchanges that can include the visually impaired on an even footing with other cooks and bakers.
Swift Playgrounds - buildable map to replicate the different maps found in swift playgrounds app "learn to code level 1".High SchoolStudents need a tactile representation of what is being visually represented in the Swift Playgrounds coding app. This app is accessible, however, students miss out on the valuable information the maps give them in order to solve their problem using code. Currently my solution is to use Duplo Legos to build these sets. An option for development is to build overlays that can go on top of the legos to indicate where a gem is, where a switch is, where stairs are, changes in terrain, etc to give more information to students. A second option is to build something from scratch that can be taken apart and put together into different formations based on the maps in Swift Playgrounds Learn to Code 1.
Storybooks or picture books for 3 student that are blind, intellectually and physically impaired Martin Elementary School of Science and TechnologyThere are really no tangible materials for these students. They are unable to read braille due to cognitive issues.
Big Bang Theory, a worm hole, the relationship between space and time, and other concepts from Stephen Hawking’s ‘A Brief History of Time’Northern Illinois University Special Education program for TVIsJoan Horvath, and engineer and author, has a discussion and models about gravity in her book 3D Printed Science Projects (the 2016 original), and 3D models of gravitational waves and a related discussion in her other book, 3D Printed Science Projects Volume 2 (2017).  Models are available on the respective Apress book sites, but won't make a lot of sense without the accompanying explanation in the books. https://www.apress.com/us/search?query=horvath.

Attribution requirement is to point back to the book and the publisher's repository.

Requesting a model from the Tactile Problem/Solution Bank

Submit your solutions:

When you have designed a solution and posted the STLs on Youmagine with the tag #tactileSolution, please complete this form.

Requested ModelsActivitiesBest PracticesTactile Graphics StandardsResourcesSoftwareInspiration


Tactile Picture Books
Contributor: Lizabeth Arum
Level: All
Duration: 4 weeks
Have students:

Prerequisites: none

Abstract the Idea
Contributor: Lizabeth Arum
Level: All
Duration: 3 weeks
Have students demonstrate their understanding of a topic covered in class by having them create a model that would help a student who was visually impaired understand the same content.
Prerequisites: none

Contributor: Lizabeth Arum
Level: All
Duration: ongoing
Do you already use tactile models in your teaching practice? Do you think those models might also work with students that are visually impaired? If so, share those models.

Prerequisites: none

Contributor: Lizabeth Arum
Level: Advanced
Duration: ongoing
Contribute to the OpenSCAD project and make the programming environment accessible. Github.

Prerequisites: Ability to program and contribute to open source project

Do you have an activity that should be added? Submit it here.

Requested ModelsActivitiesBest PracticesTactile Graphics StandardsResourcesSoftwareInspiration

Best Practices

This is an evolving resource that we hope will develop as this project evolves.

Ideally 3D printed models should be:

  • Easily reproducible.
  • Volumetric— if you are just creating an extruded version of a 2D graphic, is there another way to create this model?
  • Modles that make the Untouchable touchable
  • Models should capture ideas that cannot be easily conveyed by other means:

    • Scanned objects that are not easily accessible: artwork, body parts
    • Math equations in 3D dimensions
    • Microscopic objects
    • Very large objects

Things to Consider:

  • Size

    Don't make the model too small. If possible, make your model same size of the actual object.

    Use a reference scale symbol - with real comparison - bigger than a house, bigger than cell phone, about the size of a fly, etc.

    Tactile Perception Limitations

    • Resolution of human fingertip is 25 dpi
    • Tactual field of perception is no bigger than the size of the fingertips of two hands.
    • Color information is replaced by texture information.
    • Visual bandwidth is 1,000,000 bits per second, tactile is 100 bits per second.

  • Symbols

    Can you use symbols to indicate orientation, scale, weight?
    For example, is your model the size of a fly or house?

  • Resolution—fingertip vs pixel
  • Orientation
  • Min/Max height for raised object

    Higher things need more space around them to help discern things that are lower in height and in close proximity.

  • Perceptual details

    What is the minimum size?

    What is the minimum spacing

  • Weight

    Can you make the model have the same weight as what it represents, or can you provide information about the scale?

  • Durability

    These objects are touched and felt by hands and should not have parts that can easily break off.

  • Parametric

    Can someone easily change your model?

  • Metadata

    Include useful information (grade level, subject(s), material, dimensions, color)

  • Wall thickness

    What thickness is too thin?

  • Edge treatment  

    Models should be harmless to touch.

  • Use of braille (resist putting braille on object - use a symbols instead)

    • orientation/direction of braille
    • size of braille
    • placement or offset from edge

  • Printing Braille on 3D Models — From Jim Allan at the Texas School for the Blind

    The article Printing of Braille with 3D printers showed that in order to achieve quality 3D printed braille the braille must be printed perpendicular to bed of the printer. Braille printed at other angles can be difficult to read.


    • Spacing - Designer does not leave enough space to read the braille - Braille reading is a dynamic process. The reader’s fingers must move across the braille to read it. There should be no interfering lines, objects, textures, etc. within 10mm (TAME) of the braille on all sides.

      • inset - The designer places braille too close to edges of model and this interferes with the reading of the braille

    • Orientation - braille make sense when oriented properly. On a 3D model the user can get confused orienting the object and the braille does not make sense. Additionally, the braille orientation should match the preferred orientation of the object.


Additional Links to Best Practices

Requested ModelsActivitiesBest PracticesTactile Graphics StandardsResourcesSoftwareInspiration


Braille Standard

Common Braille characters are based on a 6-dot cell having two columns of three dots. If the empty cell is counted as the space character, 64 unique dot combinations are possible with a six-dot cell. Dot height is approximately 0.02 inches (0.5 mm); the horizontal and vertical spacing between dot centers within a cell is approximately 0.1 in (2.5 mm); the blank space between dots on adjacent cells is approximately 0.15 in (3.75 mm) horizontally and 0.2 in (5.0 mm) vertically.

Minimum Line Height – 1.6mm (TAME), braille dot height – 0.5mm

Line styles in Appendix F of BANA Tactile Graphics Guide (note: converted to millimeters)

Arrowheads – If an open arrowhead is used, the two sides of the arrowhead should be an equilateral triangle with the two sides being the same length as the undrawn base. The shaft of the arrow should be spaced 3.3mm from the apex.

The shaft of the arrow should be at least 19 mm long. If the shaft of an arrow is too short the item may look like a point symbol rather than a direction indicator.


Arrow Heads

Circle Graphs

6.3.3 – The outline of the circle should be tactually distinct from the lines separating the divisions.



Clock Face

Circle: 0.4 stroke/3mm dash/1.5mm gap, butt-capped

5-minute ticks: 0.8mm stroke, 12.5 mm either side of circle

Numbers: 6.5mm distance from ticks

Hour hand: 2.1 mm stroke with 4.2mm gap, round-capped

Minute hand: 1.5mm stroke



Grids & Graphs



Gridlines should be the least prominent lines on the graph

0.3mm stroke; 0.6mm dash; 1mm gap

Axis lines should be stronger than gridlines and include arrowheads at outer end (follow print whether double- headed or not)

.8mm stroke; solid line

Plotted line(s) should be tactually the strongest line(s) on the graphic

1.5mm stroke; solid; if line is dashed in print, make it dashed

Point of origin (O) should be included only if it is shown in print

Sometimes it is the letter O; other times it is a zero—follow print

Y label placed above (preferred) or to the left of arrowhead

X label placed at end (preferred) or above arrowhead



If space is needed, some numbers may be omitted from graph

Always attempt to show at least one axis number for reference

Numbers are placed to left of y-axis and below x-axis

No number indicator used for x- or y-axis coordinate numbers

Dots 1,2,3 should align with vertical grid lines/ ticks (ignore minus sign) and align dots 2,5 with horizontal grid lines/ticks



Shaded regions should be distinct to recognize but not overpower plotted lines or vertices

Requested ModelsActivitiesBest PracticesTactile Graphics StandardsResourcesSoftwareInspiration


Have a resource that should be added to the list? Add it here.

Requested ModelsActivitiesBest PracticesTactile Graphics StandardsResourcesSoftwareInspiration


Requested ModelsActivitiesBest PracticesTactile Graphics StandardsResourcesSoftwareInspiration




Unit Circle with Braille

by collegeofthedesert


Tactile Goodnight Moon

by TactilePictureBooks


Haptic Device Offers GPS Navigation for the Blind

Article by Meghan Brown at engineering.com


Wave Patterns for Red and Blue Light and several other models

Models by Professor Steven Sahyun and students from University of Wisconsin - Whitewater

Here are resources for two models on LibraryLyna that include how-to-use guides:

3D models created at UCDavis

To see the introduction to this project, go to the The Tactile Problem Community Project blog post.