Star Coin Project


The Star Coin project started in October 2014 as an astronomy education approach for the visually handicapped. I had recently learned how to design and print two 3D objects over several months using FreeCAD and the MakerBot 3D printers at the Case Western Reserve University think[box]. I was also working as an astronomy department volunteer at the Cleveland Museum of Natural History (CMNH) at the time. The planetarium director, Jason Davis, mentioned their collaboration with the Cleveland Sight Center teaching astronomy. Putting this together with my recent 3D printing interest, it seemed like a great opportunity to print constellations in tactile form. Jason helped set up the first meeting with the Cleveland Sight Center in November 2014. An initial test print of the Big Dipper was shown to them. The response was quite heartfelt as one person said he never really understood what the Big Dipper was until he felt this 3D model. Subsequent changes were made in sizing and layout to arrive at the designs shown on this page. Further development of the designs and methods for use are planned as the education approach is developed. Beyond the coincidence of 3D printing and astronomy there was a third opportunity that provided access to 3D printers. I had been attended a monthly meeting of electronics enthusiasts in a MeetUp group, Charged Conversation. Rick Pollack, president of MakerGear, was at one of these meetings and saw what I was doing. He generously offered to supply sets of the star coins in ABS plastic for CMNH and the Cleveland Sight Center at no cost. Great things happen in threes.

Design and Use

Each constellation is on a 50 mm diameter disk, although this can be adjusted when printed. The top of the disk has a hole so that it can be put on a beaded chain as a set. In a planetarium, sets of these could be used during the regular planetarium show. At the bottom, the three letter constellation abbreviations were intially used. This was replaced by a reference number that can be used as part of a quiz in a classroom setting. It also makes it easier for those who are not yet skilled at using Braille. Along with this, we have attached magnetic sheeting to the back of each disk (deflect-o Magnetic Vent Cover). Each student has a small metal board about 1x1 ft (from the office supply section of a discount store). The relative orientation of the constellations to each other can be taught by placement on the board. Comical stories about the proximity of constellations can make this fun for the students.

Feel free to use and distribute these. I would appreciate your feedback to help develop the materials and teaching approaches: Bruce Bream,

Field Experience

An astronomy class was held at the Cleveland Sight Center Highbrook Lodge. Cleveland Museum of Natural History astronomer Jason Davis used the Star Coins to teach astronomy in a different way. Ursa Major, Ursa Minor, and Cassiopeia were introduced and placed on individual magnetic boards. The orientation relative to the north star in Ursa Minor was explained. The boards were held up to help understand the location of the constellations in the sky above.


Great Lakes Planetarium Association meeting Star Coin Charts from April 23, 2016.

Sample Lesson Plan

Content Statement
Stars in the sky have grouped into patterns called constellations.
Humans across time have mentally connected stars they perceive to represent objects or people.

Introduce what a star is and how it produces a point of light in the sky. Stars are essentially balls of fire. Our sun is the closest example. At great distances stars are faint with some so dim they cannot be seen without a telescope to magnify the light. Magnitude is the term given to the brightness of a star.

Note how people have seen patterns in the random positions of the stars. Astronomers refer to each pattern or group of stars in the sky as a constellation. There are 88 constellations.

Hand out the star coins. Note that each point on the disk is a star. The diameter represents the star's brightness. Lines between the stars make connections that relate to the name given to the constellation.

Explain the story behind each constellation.

Each constellation has been numbered for an identification quiz.


A set of Star Coins

How many modern constellations are there?
What term is used to describe the brightness of a star?

Discussion Questions
Why did people think they saw patterns among the stars in the sky?
What other patterns do you perceive in the tactile stars?
Do you think different cultures have seen different star patters in the sky?

Science Standard
Use evidence, scientific knowledge to develop explanations.
ESS.35.5c Identify what can eb found in the solar system.

Current list of Constellation Star Coins

For each constellation in this list there is a sample image and a link to the STL file for 3D printing.

Constellation Sample
STL file Ref
Aquila Aquila.stl 18
Bootes Bootes.stl 9
Cancer Cancer.stl 7
Canis Major CanisMajor.stl 3
Cassiopeia Cassiopeia.stl 13
Cepheus Cepheus.stl 17
Cygnus Cygnus.stl 16
Draco Draco.stl 20
Gemini Gemini.stl 4
Hercules Hercules.stl 12
Leo Leo.stl 5
Lepus Lepus.stl 6
Monoceros Monoceros.stl 21
Orion Orion.stl 1
Pegasus Pegasus.stl 11
Scorpius Scorpius.stl 22
Sagittarius Sagittarius.stl 15
Taurus Taurus.stl 2
Ursa Major UrsaMajor.stl 10
Ursa Minor UrsaMinor.stl 14
Virgo Virgo.stl 8

These were the first constellation that I made. These were smaller with the Big Dipper being the first. I added Braille at the bottom to Canis Major. The final size was determined by what was needed to resolve the three belt stars in Orion.

This project is developed in conjunction with the Cleveland Natural History Museum through the support of Jason Davis and the Cleveland Sight Center with the support of Lisa Cellura, among others. ABS prints are supplied by Rick Pollack, president of MakerGear.

Creative Commons License
The Star Coin Project by Bruce Bream is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
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