Another projection of the 4-dimensional hypercube, this one close to vertex-centered. I love the shape of its hull: almost a rhombic dodecahedron, but skewed just enough to keep the central vertices from meeting.
The more usual projection is here, other polytopes are here.

A four-dimensional cube at pendant size.  Is it adorable?  Why yes, it is. Some feel it is a little large to wear as jewelry, so I've uploaded a smaller one here.

More polytopes are here.

It's a little hypercube pendant! There is a slightly bigger one here.