I have 2 rolls of (blue) painter's tape, 1" and almost 2". I use them for straight line guides, careful to not stitch on the tape. I love the serpentine stitch. On my 45 year old machine, it is labeled as a darning stitch. I like variegated thread for colorful quilts!
I would follow the seam lines of the larger squares and create a serpentine grid.