Been there,done that also. Devised this method. Cut as many 2 1/2 strips as I need, lay them side by side, right side down, except for the first strip. This one is right side up. On the remaining strips, measuring down 2 1/2" I draw a line, thus making a 2 1/2" square with a diagonal sewing line from upper left to lower right. Now I pin the second strip to the first strip, right side together and so on until all the strips are pinned together and sew. This may sound time consuming, but you should have seen my strips before I started doing this. They were all over the place,but never straight.