I am still wracking my brain trying to think how you could make the bracers and I'm absolutely stumped. I have never seen any sort of sports forearm guards that completely surround the arm... at least not that I can recall. Roller derby wouldn't use such things, I checked some sites that sell MMA and other martial arts equipment and didn't see anything close enough, checked sites that sell motocross gear, even looked at Galls to see if they had something under their training gear or even tactical body armor, and no dice.
I did find these, and they look like they may be hard plastic and could be painted, but I have no idea if the plastic extends around to the underside of the forearm as well. My guess would be no, for ease of wearing, but you never know. Could maybe email them and ask. Title's a pretty reputable company from what I know so their customer service may be helpful in this regard.
I definitely saw some stuff that could look badass (esp. among the MA/MMA, cycle, and law enforcement armor), but not anything that would match the look in the pic with hard guards over the inside of the arm.
The shoulder pads would obviously be just football pads?