I used most of a skein of Big Twist as my “background” color and odd balls from stash in rainbow stripes for the second color. I changed color families every foot so the full scarf is 6 feet/1.8 meters long.

It’s 14.5 inches/36.8 cm around (so 7.25 inches/18.4 cm wide) but you can adjust to make it as wide or narrow as you like.

Pattern includes tutorial for helical knitting (aka helix knitting).