I didn't know this how-to when i made these, but it's totally what i did, so it's even a version :)
I used child's pants, so that's why i can put them only under the knees.
From old pants to Awesome Legwarmers and enough extra to make shorts or something
Stevie Nicks Awesome Gathered Ruched Velvet Legwarmers
Furry Leg Warmers size small