Bricard's Flexible Octahedron

Raoul Bricard discovered some flexible polyhedra that are impossible to build out of paper because faces pass through each other. However, if you remove two faces from his flexible octahedron (and in effect create a polyhedral linkage); you can explore how the octahedron flexes.

Steps

1. Print the pattern and use it to cut out a model out of boxboard. This model works better if you create it out of something more rigid than paper. You can use the packaging from a box of cereal for example.
   
2. Score the fold lines.
   
3. Fold and glue. Mountain folds are dot-dashed lines and valley folds are dashed lines.
   

References

• (Goldberg, Unstable Polyhedral Structures 1978), (Cromwell 1997), (Goldberg, Polyhedral Linkages 1942)