Using a 1/2" seam sew all the way around the piece leaving a 3" opening at one end. Make  sure to back stitch at the beginning and end of each seam.

Snip off all 4 corners.

Through the 3" opening pull the scarf right side out.

Make sure to poke your corners out until they are nice and pointy. (I usually use a knitting needle for this.) 

Iron the whole thing flat. Pin the 3" opening together, with the raw edges inside.

Baste both sides together with curved safety pins placing one every few inches.

Slip stitch together the 3" opening. (If you need a slip stitch refresher click here.)