 Articles
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Snub Expanded (0,0,12,17)deltahedron
(0,0,12,38)deltahedron consisting of 6 hexagonal modules (containing 2 spheres connected to 5 rods) with rows of triangles in between. It is completely rigid, and highly reminiscent of Alain Lobel's 
Augmented Truncated Dodecahedron
There are two (regular) ways of augmenting a Truncated Dodecahedron with pentagonal cupolae: cupola pairs connected squaretosquare (CS2S) and connected triangletotriangle (CT2T). The Truncated Dodecahedron may also be augmented with pentagonal 
Lunarholed Rhombicosidodecahedron E5/6J91(P4)
The Lunarholed Rhombicosidodecahedron, Stewart's E5/6J91(P4). This is a Rhombicosidodecahedron (called E5 by Johnson), with a 6way hole through it made from Stewart's 6J91(P4), as described on pages 128 
General Deltahedron
Polyhedron (homeomorphic to a sphere) consisting of equilateral triangles only. If we define the valency of a sphere as the number of rods connected to it, and write the number of spheres with valencies 3 
Tori
To make a sphere is easy (any of the truncated icosahedra will do), but how to make a torus? I used a small icosahedron as starting point, and bent it open at two pentagons having 
Truncated dodecahedron
Geomag doesn't come with decagonal panels, so they must be approximated with pentagonal cupolas. There's a rather surprising choice to be made when building this model: which way do I orientate the cupolas? 
PrismExpanded Dissected Cuboctahedron
The PrismExpanded Dissected Cuboctahedron is a Stewart Toroid that has a convex hull, but not all faces of that hull are regular. This particular toroid was discovered by Alex Doskey, which he named the 
Drilled truncated icosidodecahedron
Geomag realization of a large Stewart Toroid, named in the spirit of Stewart's Drilled Truncated Dodecahedron, which inspired this model. The original Drilled Truncated Dodecahedron has pairs of triangular faces (where the edges of 
Rhombic Triacontahedron (Internally supported)
The rhombic triacontahedron is made from thirty golden rhombii, with the sharp ends meeting at twelve valency five nodes, and the shallow ends meeting in twenty valency three nodes. It is possible to build a 
Pseudosphere From Geomag Box
This page will discuss the idea of building a spherelike polyhedron ("pseudosphere") based on completing the spherical shell shown on the cover of the 350 Geomag Case shown below. I was particularly intrigued since it 
Diamond
The diamond lattice gets its strength from the intricate interconnectedness of its basic carbon atoms. This model of the elementary lattice cell shows how each (yellow or green) carbon atom is connected (in red) to 
Geomag Weights and Measures
A Geomag Rod is 27.00mm long, and has a maximum diameter of 7.40mm. The spheres are 12.70mm in diameter. With use the rods may become slightly compressed, by about 0.1mm. 
Creased Platonic Deltahedra
You can make families of large Platonic solids with triangular faces (deltahedra), made sturdy by`creasing' their edges to become domelike. The shapes that results are all deltahedra, and although the principles of construction 
Truncated Octahedron
Number of Faces: 14 (6 squares and 8 regular hexagons). Number of Vertices: 24 (2 hexagons and 1 sguare). 
Conservation of Angular Momentum
Use this very simple construction to demonstrate the principle of Conservation of Angular Momentum. The Geomag Manual describes this as "DANCING BALLERINA EFFECT”: the principle of energy conservation"; the original demonstrations described here follow those 
Penrose C4 Cartwheel
This is a placeholder for a Penrose C4 cartwheel. It can be built using the property that if you build a triangular pyramid on top of two connected rods that are spanning an angle of 
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Truncated Cuboctahedron of Cubes
It's a truncated cuboctahedron on the outside, and a rhombicuboctahedron on the inside, and the two are connected by the cubes. Totals given in the summary box. 
Stewart's 6J91(P4)
Stewart's 6J91(P4)  Six bilunabirotundas (6J91) surrounding a central cube (P4). Although the Geomag model shown at the right retains the inner (yellow) cube inside (for extra stability), this is not part of 6J91 
Amafirlian Square
An Amafirlian Square is an alternative way of joining Geomag rods by connecting 4 rods in a cross wise fashion. As a result they can replace a rhombic face. An example can be seen in 
Suspended Circle
A fully suspended closed circle on two support legs. The loop is composed of 34 segments, alternating trianges with pyramids. Let alpha= arcsin(1/sqrt(3))= 35.264 degrees, be the semiapex angle of 
Curved Triangle Using 30gon Circle Arcs
This is a simplified form of the Curved Triangle that appears on page 92 of Stewart's book (Example 4, 2nd edition only) [I finally got a copy!]. The form presented here differs from Stewart 
Stellated Rhombic Triacontahedron
Stellated form of the rhombic triacontahedron, also known as the rhombic hexecontahedron. This model is supported internally by a spehere with valency 12. It consists of 20 golden parallelepipeds. The small diagonal is about 5 
(0,18,0,80,24)deltahedron
Starshaped (0,18,0,80,24)deltahedron consisting of 8 convex spheres connected to 4 rods (forming a cube), and 12 concave spheres connected to 4 rods (forming an octahedron). It is completely rigid 
Spiral spheres
This is a spherelike object with a spiral running from North pole to South pole. It is a member of a family of such spiraled spheres, which can be made all the way down
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