It is easy to find vintage cape patterns online. I used McCalls' 9028 from 1967, but McCalls' 9550 from 1968 is readily available on Etsy and I think it is a nicer pattern. It wasn't too difficult to make, but I had some trouble with the lining. As a result, I am not thrilled with the way it drapes, but I don't think this is something I will wear very often.
I wore this cape the night of Nuit Blanche, and while my friends complimented me on it, I got a lot of weird looks while walking around at 3AM in the freezing cold. I also got a "Nice poncho" from a drunken lout (unfortunately, Nuit Blanche crowds seem to be primarily made up of boring drunken louts, and also of clove cigarette smokers, yuck). Still, a new friend who lives in New York told me he liked it and identified it immediately as "so APC." So that was nice.