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.