I used knit picks cotton yarn, called "Billow". It's a bulky thick-thin yarn and I love love love how soft it is! It is one of my favorite yarns, that I also used to create a bunch of hats with last year for my infertility and miscarriage group.
These colors begged to be a cowl. So I made one. For myself! And the pattern is my own. Although, stripes are easy and don't require much forethought or ingenuity.