LED throwie is a great project from Graffiti Research Lab.
So, as a contribute to their project, I made a “Granny Throwie”, LED throwie made with crochet.
It does not have magnet inside, so actually you can not really “throw”, but you can “knit tagging” with it. Since the batteries are embedded inside, and it is not really possible to change it, I made it as a button. LED turns on when you press the middle… well, for tagging, it will be better to make it always on.
The second version has a light sensor on it, that it will only turn on when its dark. This will be better for tagging.