How To Sew Amigurumi Parts Together
Sewing amigurumi pieces together can feel a little tricky at first, but it becomes much easier once you know the basic technique. The goal is to attach each piece neatly, securely, and in the correct position so your finished toy looks balanced and well-made.
Once you finish a new part of an amigurumi, if it is a piece that is open at one end, you must first do an invisible fasten-off. Since this piece will be attached to the base piece around its perimeter, you need to cut the yarn, leaving enough yarn to go around it 3 or 4 times. To do an invisible fasten-off, you can check our article here. You will use a tapestry needle and go through the 2nd stitch on the hook, and then turn and go under the back loop only of the last stitch on this row.

You can continue to stuff the piece slightly to give it some volume before attaching it.

Start by pinning the pieces in place before sewing. This gives you a chance to adjust the placement before anything is fixed permanently.

Using the same yarn of the piece you are attaching with a threading needle, you can now start sewing it around its perimeter. Start by inserting the needle into the closest hole on the base piece and exiting through the hole on the other side of that stitch.

Now, from the inside towards the outside, insert the needle under the stitch on the piece you are attaching, right on top of where you exited the base piece with your yarn. Then you will insert the needle from the outside towards the interior under the next stitch on the piece you are attaching.

Continue sewing back and forth around the edge, catching one stitch from the body and going around two stitches from the attached piece each time. Pull the yarn firmly enough to hold the piece in place, but not so tightly that it distorts the shape.
As you sew, pause every few stitches to check the position and shape. If the piece starts to tilt or creates a gap, adjust it right away. For larger parts such as heads, legs, or tails, sew slowly and evenly all the way around to create a secure, tidy finish.
When you are finished, enter the yarn into the base body and exit on the opposite side. You could cut it close to the surface, and it should stay in place.

If you want to make it extra secure, you can pick one loop next to where you exited with the yarn, pull the yarn through it, and insert it back into the same hole. Pull tightly and exit somewhere else on the body. This will make an invisible knot and you can safely cut the yarn on the surface.
