In addition to using a light weight stabilizer to prevent raveling, you might try sewing a straight line around the pieces. I know that is a lot of extra work, however, when I first started sewing my clothing and the fabrics back then raveled a lot, so I sewed around each piece, which kept the fabric from fraying, as the stitching stopped the fraying when it met the stitching. I'm looking forward to seeing the finished quilt.