I use a 120" measuring tape to measure the quilt and the next border strip. I use a long table (or two)or the floor and use a small cutting mat with ruler (each wider than the border). I lay the border so one edge follows a line on the mat and slide the mat under the border so a vertical line is right on the measurement I want and under the measuring tape. I slide the ruler in place on this cutting line, matching up the lines on the mat so the cut is square with the edges of the border. Remove the measuring tape and it's ready to cut.