I was unable to find a replacement hub-cover for my old 1997 Toyota 4Runner that matched the finish of my wheels, so I measured up the old one and attempted to make a copy in plain black. It seemed to turn out OK! Though, I ended up trading in the truck before I could make any refinements.
It seemed to fit securely and look OK, so, I thought I might share my results with everyone else. I doubt it's quite perfect as I measured and drafted this from scratch rather then being a scan or anything. So there were a few guesses here and there. I hope at least it might make a useful base for someone in the future, but since I no longer have the truck, this is pretty much as-is.