I had made a gray one of these last month for my daughter, and when my friend saw it she immediately wanted one :D
So due to her desire that it be machine washable and the huge amount of yardage required, she bought 2 skeins of Lion Brand Pound of Love in mint green.
I modified the original pattern to include a hood and a zippered closure. This one does not have the zipper yet, but my friend has a sewing maching and will put the zipper in herself.
The original pattern can be found here: