Central model of
the cube inversion.
(J.P. Petit 1991, imagery by C. TARDY)
This is the polyhedral version
of the central model of the sphere eversion by B. Morin
(see the article in the January 1979 issue of Pour la Science).
Why "central model"?
Because this model represents a cube, for example green on the outside and yellow on the inside,
half-inverted. It therefore has "four ears," alternately
green and yellow. If there exists a sequence of transformations that
turns the cube into this model, the inversion is achieved, since it
suffices to rotate the model by 90° around its axis and then reverse all the transformations.