https://www.cutoutandkeep.net/projects/three-needle-cast-off • Posted by Search Press
Divide the remaining stitches evenly between two needles. Fold the knitting so that the right sides are together.
Using a third needle, knit the first stitch from each needle together.
Knit the next stitch from each needle together. Cast off the first stitch in the usual way, by lifting it over the second stitch.
Repeat until all the stitches have been cast off. Turn the piece the right way out before sewing up.