It's not the PaperJuke one built by Pete, but I have found another free download model of Capt America ... two in fact ... and lots more goodies by a Brazilian artist.
Unfold Brazil: Personagens
Top of the list is Capita America 2099 ... it's a woman
But if you scroll down to page 2, ignoring all the other fantastic figures along the way, you'll find the original Captain America.
Be warned though ... these are .pdo files that will only open using the latest Pepakura v4.
I've just hooked into his Facebook page too ... very interesting.