This literally took 3 minutes to make and is super warm! I made it out of a sweater that was too small for me cut it just below the armpit area and ta-da! You have a lovely infinity scarf that would cost $20+ at the store.
Advice: It will take a nice folded form once you wear it. So dont sweat it if it looks funny on you after you cut it.
Looking to funk it up a bit? Add buttons! (yes, thats my answer to everything)