I have done sashiko - am doing some now. I have a novel approach to getting the design onto the front of the fabric. I copy what ever pattern I like onto freezer paper via the copier and iron the freezer paper onto the front of the fabric and then using my DSM stitch on the lines thru the freezer paper. Rip off the paper and sew the sashiko stitch right next to the the sewn lines - when done I rip out the DSM sewn lines. More work but not too much and you don't have to worry about the marking lines not washing out. Sashiko fabric is thicker or more dense cotton and I have found that the marking pens are hard to get out without leaving a residue. This method you can use any design you want and you don't have to be able to draw.