Projective Space

This is a model of the smallest projective 3-dimensional space in existence.  To be slightly more specific, this is the 3-dimensional projective space over the two-element field GF(2).  There are 15 balls representing the points of the space.  The 35 lines of the space, each possesing precisely 3 points, are represented by 10 ellipses and 25 line segments.  According to Burkard Polster (in his "Geometrical Picturebook"), this design as based on the tetrahedron was discovered by Dale Mesner.