RULES OF SYMMETRY
I apologise for not explaining these in the course of my post for 'Reflections'. I am afraid that I did not give thought to whether members were acquainted with these so I shall try to put matters right.
Very briefly, these rules form the basis of all pattern repeats & apparently the building blocks for crystallography & some of Escher's work as well. They include arrangements such as mirror, flip, drop, half-drop, glide etc. I can point you to some books which should help. The best one for quilters is probably Ruth McDowell's 'Symmetry' as she uses a hand symbol to illustrate the various orientations. Also useful is Jinny Beyer's 'Discovering Tessellations' & Peter Phillips's 'Handbook of Regular Patterns'. An Internet search will reveal 'Wallpaper Groups' on a Clark University site. These amount to the same thing but are a bit complicated if you are unfamiliar with the principles.
I hope this helps. If you still cannot find anything e-mail me.
Is there going to be a new challenge soon?