I love this braided scarf concept. It looks great, it'll be reversible, it won't come undone or need readjusting, it's a good way to showcase a beautiful hand-dyed yarn, and it'll be very warm. The pictures here do a great job of showing you how to make such a scarf, though I'd knit the three parts of the plait up one at a time using a set of double-pointed needles or the magic loop method, leaving the ones I'd done on a holder, rather than using a circular knitting tool as in these pictures.
I know some knitters will want more explicit directions, so I searched for a pattern, but was unable to find one as good as this. Most of the braided scarf patterns I found just sewed the braid together at the end, which doesn't look nearly as good as knitting them together. If you can find a pattern like this, flip me the link via email or in the comments and I'll add it to the post.