This page introduces a very important math concept that is imbedded in the frame building process.  It is the notion that parallel lines stay "parallel"----that right angles remain "90 degrees".  This sounds simple enough but is crucial to all the other elements in this build progression.  The picture to the left will access an important article on this procees.  The other images below will also access additional imformation on this plus the essential tools to get the job done.