|I've always been frustrated at measuring seam lines using the usual technique, holding the measuring tape on its edge. Measuring tapes are floppy and don't really work well unless you're very, very meticulous, and then the measuring takes forever.
Yesterday I was working on an altered princess seam and just by holding up the front and side front together, I could see that I had made a mistake somehow, since one piece was about two inches longer than the other. Grr. I needed to measure those two seam lines!
Fortunately a light bulb went off. I have one of those flexible plastic C-Line rulers, 12 x 1 inches. I held it on its edge, curved it beautifully around the princess curves, tipped it up on its end, flipped it over to the other edge, and continued down to the end of the seam. Voila! 12 inches plus 1 inch for the end, then 12 inches and so on to the end of the seam line! And I was right. There was 1-3/4 inches differences in the two seam lines. Back to the drawing board!