Fusible thread has been around for decades. Superior brand has better quality of those I have used. I sometimes use it in the bobbin to stitch around my quilt top and then when I sew the binding on a large quilt. I can turn it an fuse it in place to hold it perfectly while stitching it by hand. Don't have to remove the top thread and can use left over thread of any color for the top. I think I paid about $6 a spool.