Cuts · Platonic solids

Dodecahedron

3D model · 12 faces · 10 mm circumsphere

Twelve regular pentagons, meeting three at each of twenty vertices, dual to the icosahedron. Of the five solids it fills the most of its own circumsphere.

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About the dodecahedron

Twelve regular pentagons, meeting three at each of twenty vertices, dual to the icosahedron. Of the five solids it fills the most of its own circumsphere.

No crystal grows in this shape, and none can: a regular pentagon carries fivefold symmetry, which no repeating crystal lattice allows. The two minerals often taken for it are something else. Pyrite's pyritohedron has twelve pentagonal faces, but irregular ones, and garnet's rhombic dodecahedron has twelve faces that are rhombi.

Dodecahedron specifications

Taken from the delivered model and checked against its mesh every time this page is built.

CategoryPlatonic solids
Faces12 regular pentagons, all congruent
Vertices20, 3 faces meeting at each
Edges30, each 3.568 mm
Schläfli symbol{5,3}
DualThe icosahedron
Dihedral angle116.565°, the same on every edge
Size9.822 x 9.342 x 7.947 mm, resting on a face
Circumsphere10.000 mm across, through every vertex
Midsphere9.342 mm across, touching every edge
Insphere7.947 mm across, touching every face
Surface area262.87 mm²
Volume348.15 mm³
Sphere fill66.5% of its circumsphere
Isoperimetric quotient0.755 (a sphere is 1)
Weight at this size6.13 ct in diamond, 5.61 ct in moissanite
OrientationMillimetres, Y up, one face resting on the ground plane, centred on the Y axis
FilesSTEP, 3DM, STL, OBJ, FBX, GLB. 3D files only, no cutting files

Dodecahedron: questions

What files come with the Dodecahedron 3D model?

Six formats: STEP (the exact solid for CAD), 3DM for Rhino, STL and OBJ meshes, FBX for Blender, 3ds Max, Maya, Cinema 4D, Unity and Unreal, and GLB for the web and AR. All are in millimetres at real-world scale, with 12 flat faces.

Is there a cutting file for the Dodecahedron?

No. The Platonic solids are sold as 3D models only, with no faceting design, tier table or diagram.

How big is the Dodecahedron model?

It measures 9.822 x 9.342 x 7.947 mm resting on a face, with every vertex on a sphere 10 mm across. All five Platonic solids share that sphere, so they nest and sit together at true relative size. Scale it uniformly to any size: for a 10 mm edge, scale by 2.8025.

How is the Dodecahedron model oriented?

Y up, with one face resting on the ground plane and the centroid on the Y axis. The midpoint of one edge of the resting face lies on the +X axis, which keeps the cube square to the axes.

Can I 3D print or cast the Dodecahedron model?

Yes. The mesh is watertight and manifold, with outward normals and no duplicate vertices, so it prints and casts without repair. Use the STEP file when you need the exact solid in CAD.

More Platonic solids

Get the Dodecahedron files

6 formatsMillimetresWatertight

Dodecahedron 3D files

The dodecahedron as exact geometry: 12 flat faces, real-world scale, ready for CAD, rendering, printing and casting. The Platonic solids are sold as 3D files only.

  • STEPExact faceted solid for CAD
  • 3DMRhino, closed mesh on its own layer
  • STLWatertight mesh for printing and casting
  • OBJMesh for modelling and rendering
  • FBXBlender, 3ds Max, Maya, Cinema 4D, Unity, Unreal
  • GLBWeb, AR and quick previews
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