I found this metal cuff blank supplier while looking for supplies to try and make Gary's bracelet. I haven't purchased yet, so I can't recommend them, but wanted to share the link in case you're having the same trouble I did finding the metal cuff used in the tutorial.
http://www.beadwork-supplies.com/braceletblanks.html
If you do use them, I'd be interested to know what you think. Unfortunately, I've had to put this project off until after the holidays.