Eucsyms invites you to visually explore the (euclidean)
symmetries of crystals.  First, choose a symmetry using the 
browser on the main panel.  The objects that you now see in
the geomview camera together possess the symmetry that you
have selected.   If you fly around using the usual interaction
in geomview you may get a better sense of how the objects
occur in a repeating patterns, demonstrating three dimensional
symmetry.  To modify the symmetry, you can change the relative 
positions of principle translation vectors 'x' 'wye' and 'zed' 
(except when the lattice is cubic).  Modification of the
objects in the geomview camera is done in Maniview-- try
moving the sliders under 'Basic Tile'.  Any object that
geomview knows about can be specified (under 'User Geometry')
as the 'Basic Tile'.  Comments on this program are welcome.