I was leaning on towards getting a canvas material cloth and dying it Olive Drab - but in the end I ended up getting this off of eBay ($13.50 +$6.00 S&H)....
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I figure I can make a decent cape out of this, plus I see the 501st CRL states that it should be made from a US Army half shelter! I also see that they don't give an "Official" size of the cape itself, but does state that the cape should not go more than 4-5" past the left knee strap. I'm guessing that's because that's how it looks on Fett - and the various different sizes of Cosplayers out there.

I'm still waiting for my Boba Maker Collar/Back Armor to see what size those Square Studs are so I can judge what size of Grommet(s) I should get.
Thanks,
-Iron