You can make something out of fully assembled neckties if you want.  I recommend washing them by hand first, especially if they've been well used.  Air dry, then press.  (Dry cleaning is always an option, but an expensive one.)  Sew together for your project using a zigzag stitch or, if your machine has one, as bridging stitch.  Or you could overlap the edges slightly and sew with a straight stitch through both ties.