In honor of the cold weather (-39 degrees with wind chill this morning) I thought I'd share my tutorial for No Sew Legwarmers. It's not scientific and I've only done it twice but it's easy to do and you can use up an old sweater no one wants to wear anymore.
Full (aka felt) a wool sweater. You'll probably want one at least one size up from what you usually wear. Before you full it check that the wrist cuff can comfortably fit up over your calf. I used two XL sweaters for my legwarmers (I wear size M or L). Full the sweater by washing it in your machine with hot water and soap, rinse it on cold (the temperature shock does awesome stuff to wool) and then you can either dry it in the dryer or let it air dry.
Cut off the sleeves. Cut on the outside edge of the seam. You want a clean edge (don't worry, it won't unravel).
You're done! Legwarmers in a flash!