I made a Super Square today, its 59 inches to a side. I scribed a center line on 3 straight scrap narrow boards, 2.5 to 3 inches wide, then marked a starting point near one end of each and using dividers stepped off one with 3 divisions, one with 4 divisions and one with 5 divisions and then drilled 1/4 inch holes for carriage bolts and used fender washers and a nut to tighten it together. I got an upcoming use marking 30+ inch wide roofing tin for my new roof.