how far off? can they be trimmed to be all the same size? often if you square up/trim your blocks after stitching you can easily get them all the same size before sewing them together. before putting them together practice getting that 1/4" seam consistent. cut a stack of 1 1/2" strips x 6" ... sew 3 together- measure the center strip, it should measure 1"...if it does not look at your seam, determine why- *too wide? too narrow?* adjust & try a new group of strips---until you get it right- then either mark your machine or use a piece of tape, stack of post it flags, a cut index card...what ever to use as a guide to help you line up & sew your 1/4" seam consistently.