How to finish an open edge with the invisible fasten off for lefties
For amigurumi pieces that'll be sewn onto another piece but with the edge still visible, there’s a slightly smoother way to finish the piece. Like the regular fasten off, once you’ve finished your last stitch, cut the yarn to make a tail. Remember to leave a tail long enough so that you can use it to sew this open piece onto another piece.
How to do the invisible fasten off in crochet (step-by-step with photos)
For pieces that’ll be sewed onto another, or for a piece where the edge will be seen, you can use a technique called the “invisible fasten off.” This technique makes the edge look smooth.
 1. Finish the last stitch and cut the yarn so that the yarn tail is at least 6 inches longer than the circumference of the rim of the piece. |  2. Pull the hook away from the piece until there’s no loop left on the hook. Thread a needle with the yarn tail. |  3. Skip the next stitch. Insert the needle under the top loops of the stitch after that, from the outside to the inside of the piece. |
 4. Before pulling it tight, insert the needle under the back loop of the stitch the yarn tail came out from. |  5. Pull the yarn tail tight enough so that it’s the same size as the other stitches along the rim. |