So when I saw this picture in the final episode of the season ("The Best of Both Worlds, Part 1"), I immediately wanted to figure out how to knit it. But I think it might just be one of those things I do just to sock it away for any future (and I mean fuuuuuture) children-of-my-own.
It's definitely got to have earflaps and some sort of snap beneath the chin, and the tubing can be done with i-cord. The "brim", I'm not so sure about, but I'm leaning toward something like ribbing that's picked up/continued in such a way to give it a layered look.
As for the chest implant? Totally something you can button on a shirt and then hook pacifiers to. Clearly. Isn't that what all borg babies do?