Place your block on your rotary mat so that it square with the lines on the mat. Take you rotary ruler (my favorite one is 4″ by 16″) and put it at a WONKY angle on top of your block. If the top of the ruler goes to the right like in this example, the block will rock to the left. If the ruler leans to the left on the first cut, the block will rock to the right. I like to make sure that I have at least a 1/4″ seam allowance of my sashing fabric left after the cut. See in the lower right corner of my novelty print? I have made sure that there is enough fabric for a seam allowance. Make the cut!