Great Icosahedron

 

Great Icosahedron

This model can be made in 5 colors. There are 120 pieces to be cut and assembled.

To see the full-sized template click on this image:    great icosahedron template

In his book, Polyhedron Models, Father Wenninger lists the colors of each star shaped vertex with a small error. I have corrected his color suggestions in the following table.

    1 2   3 4   5 6   7 8   9
10
(0) Y G B Y O B R O G
R
(1) B G Y B R Y O R G
O
(2) O Y B O G B R G Y
R
(3) R B O R Y O G Y B
G
(4) G O R G B R Y B O
Y
(5) Y R G Y O G B O R
B

              great icosahedron alignment

Arrange the pieces as shown in the picture above and to the right. To create a star shaped vertex, you will have to fold your pieces so that there is a valley between piece one and two and a hill between piece two and three. Each vertex will be folded repeatedly up and down. The bottom fold of piece 1 will then be glued to the bottom edge of piece 2 to create a dimple. Continue to connect the bottom piece of 3 to 4, etcetera and you will have created a base cup that contains a pentagram shaped pyramid.

When vertex (0), (1), and (2) are connected in a counterclockwise order, you must arrange them so that the section containing those 3 pieces is a blue sided bowl. (In the finished polyhedron picture above, we are looking at a green sided bowl formed by 3 vertex pieces.)

Vertex (3) can then be attached continuing in the same direction around vertex (0) so that this next completed bowl is orange.

The table above gives only the first 6 vertices. The next 6 vertices are enantiomorphic to the first and placed diametrically opposed to their corresponding partners.