I have several turtle neck sweaters they don't look good on me anymore I made one into a cardigan, I cut the top of the neck off and added a bias binding in silk or polyster (the kind that has a sheen to it) they turned out great so pleased with them. I wasn't sure if it could be done also I can now wear them, this summer under my jackets so many places have air that Im always needing something on my arms. If the fabric is very streachy I found you could use some wash-a-way stablizer on the top and bottom to allow it to feed through your machine. Then cut close and wash the neck of you sweater. I hope someone can use my experience if you need more info let me know.