This winter, which has my house more full of freezingness than I remember in previous years, I finally get the point of a cowl. And now I have one:
Here's how it started, as a partially-felted Banana Republic sweater (90% merino, 10% cashmere, and boy can you feel that 10%):
I cut off the body just below the arms, not even very neatly:
and then I turned it wrong side out, folded the cuff up, and folded the cut edge down far enough to tuck into the cuff.
This sweater felted down to 34" around, with 11" from cuff to armholes; folded, it's about 4" deep.
I'll try this approach again with a sweater that felts narrower, because I think this one's gap is about as big as I'd want. In a floppier wool I'd only fold it once or maybe not at all, and blanket stitch the raw edge since it would show. This sweater was heavy even before it felted and doesn't drape enough to be tall for indoor use. (outdoor, folded into a coat, definitely.)
Even at this size though it's still deep enough to tuck my chin into and go all Veronica Lake-y,
so between that and the cashmere I'm happy!