Your mission, should you choose to accept it, is to join the two unfinished ends of the scarf. You would best accomplish this by using a kitchner stitch--with needle and thread, to graft the ends together to provide a seamless seaming invisible even to the practiced eye!
First, now that the individual pieces are blocked, you should place the live stitches on straight needles. You could also use a long circular, putting one side of the needle through one half of the scarf and the other end through the other half of the scarf so that both ends of the needle have a piece of the scarf where each is right side facing you, then fold the cable in half so that wrong sides are facing each other. If you decide to use straight needles, just hold both needles so that wrong sides are facing each other and both needle tips are pointing to your right. This of course is dependent on the idea that you are right-handed. Hold one needle in back and the other in front.
The biggest thing to remember is to do this work loosely--you can snug things up later!
With a standard sewing needle threaded with a length of yarn, and using the sewing needle as if it were a knitting needle, begin by purling into the first stitch on the needle closest to you, and pull the yarn through so you have a tail long enough that you can use it to weave in the end later. Continue by knitting into the first stitch on the back needle, then knit into the first stitch on the front needle. Drop the first stitch off the front needle. Now purl into the next stitch on the front needle, and then purl in the back needle stitch and drop it off the needle. Knit into the next stitch on the back needle. Knit into the stitch on the front needle, drop it, purl into the next stitch. Purl into the stitch on the back needle, drop it, knit into the next stitch.
Notice that as you are working the stitches you only drop the stitches when you are working the same stitch pattern--knit for the front, purl for the back!
Continue in this zig-zag pattern until all stitches have been worked off the needles. Set the sewing needle down and allow the grafting yarn to hang free. Lay the work on the ironing board and, beginning at the center and working outward, snug up the loose grafting stitches so that they resemble your knitting. Weave in your ends.
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