I have written the pattern for three colours but you can make it with just two if you like. As you read the pattern it will become obvious how to incorporate fewer or more colours. My preference is to use a very light Aran (worsted) weight wool for the main colour that forms the triangles, and a slightly lighter DK paired with a mohair for the backing colours. However, if you’re not a mohair fan, just use the same weight yarn throughout.

The pattern is entirely written out. No charts.

The pattern is written in two sizes, for a more snug cowl which only goes once around your neck, and for a larger cowl which loops generously a couple of times around.
Finished measurements
After blocking: Large (small) 160 (64) cm long (total circumference) x 26cm wide (depending on how hard you block)
Yarn
(If using mohair, hold double with CCs, and make sure CCs are one yarn weight lighter than your MC)
If you struggle to find worsted weight, then you can also hold fingering yarn (400m per 100g) doubled up which adds a nice feature (and is what I did in my pink version).
Main colour (MC): Worsted (light arran) weight, white 100g (200m). NB – as this requires 100g of yarn, beware that you could end up needing a little more than one ball (1 in 10 testers required more than 100g). Either be ready with a second ball, or be prepared to do one fewer pattern repeats.
Contrast Colour 1 (CC1): DK dark pink 50g (110m) - I originally used hand dyed cocheneal from Burt Fen Alpaca
Contrast Colour 2 (CC2): DK light pink 50g (110m) - I originally used hand dyed cocheneal from Burt Fen Alpaca
Mohair (always held double with CC1 and CC2): white, lace weight (8-900m per 100g) 
Needles + notions
● US size 7 needle / 4.5mm needle for main body. 
● A 5mm is also useful for the cast off - but not the end of the world if you don’t have one. 
● 100 or 160cm circular needle (use a 50cm one if you’re making a smaller size)
● Stitch markers.