I love tumbler quilts..I do a pretty good job matching the seams but sometimes a few get off a bit and I find its normally caused by the think seams when sewing the rows together. I decided to try ironning my seams open...WOW what a difference....My seams look great and not lumps. Not only do the seams line up prefectly...it also will be alot easier to FMQ less bulk. So why do we iron the seams to the side instead of open seams??? I also sew my strips twice...once each way. I find its a great way to see if I sewed a piece a bit off....and its prevents waves.