Much Googling later and I came to the conclusion there wasn't much out there. There were a few pictures of simple single-hinge wings but those weren't very impressive to me, and the professional version was well over a thousand dollars and not what I was trying for anyway.
Since there weren't many how-tos out there, and since nobody had really done what I wanted to do in an affordable (mostly) way, I tried to take some pictures and help others who want to build wings that open and close without manually pulling strings.
Steampunk Hawkman is the result. This is a tutorial on building his wings (V1.0).
Step 1: Planning
They're fairly similar, although skeletally they're a bit different, so I chose bird, just because there's more of them out there.
This diagram shows a greatly simplified way of creating the parallelogram that does the work. When the base of the wing is attached at the ends, moving any of the members should cause the wing to fold and unfold.
Originally, due to all the manual wings I saw, I thought only about pulling or pushing on the attached ends, but once built, it became clear that any change to one of the angles affects all the rest. That opens up a lot of ways to cause the folding motion.