difference()
{

        union()
        {

                <your design>

        } // union

        // difference the debug hole
        difference()
        {
                #translate([-10,-10,-10])
                cube ([190,160, 60]);

                // print hole
                //cube ([170,140, 35]);

                #translate([85,-10,-10])
                cube([105,150,300]);
        }


} // final difference