difference of unions

difference_of_unions.scad

/*
 * module template for creating complex structures in openscad
 * uses a difference of two unions
 * the first union contains all openscad entities that make up the 
 * outline of the object
 * the second union is for shaping by cutting away
 */
module foo()
{
    difference()
    {
        //first union with all structures that define the object
        union()
        {

        }  //union 1
        
        //second union with all structures that need to be cut away
        union()
        {

        }  //union 2
    }  //difference
}  //module