I started this on the plane back from Zurich. It took about a week to knit- it wasn't easy to memorize this pattern and the cables were pretty complex. It's PAY ATTENTION knitting.
Once I was done, two thing occurred to me.
1. Gauge swatches should have been made in the cable pattern, lest you want to end up with a feedbag for your head.
2. Very few people can pull of The Wearing of the Tam.
It ended up being huge. I threw it in the wash machine twice (I only have access to a front-loader, so it took the guesswork right out of the felting process) and then threw it in the drier for 10 minutes before taking it out and blocking it over a dinner plate and letting it dry on the radiator. The stitches tightened right up and the cables popped. Once it was dry, it was deemed wearable. Just not by me.
I used a bit over 2 skeins of Rowan Yorkshire Tweed, which is a discontinued dk weight yarn. It's a 2-ply yarn that is a bit undertwisted, so it wouldn't stand up to a lot of wear and tear.