Nolids are 3D shapes that contain no volume. They are related to the Kepler-Poinsot polyhedra in that they are made from intersecting polygons, but differ in the respect that they have no volume.
The pics below are a nolid I designed from 4 intersecting regular hexagons. If you did join the edges to make faces for this shape you would get a cuboctahedron. I made this after being inspired by the excellent book Shapes, Space and Symmetry by Alan Holden.