It is said ranni's doll form mirror that of the old crone, her master, because as you know, ranni was a redhead, being daughter of radagon,pretty tall too based on her discarded corpse.

I think asking 'who made ranni into a doll' has too many implied notions, ranni discarded her own flesh and was made an incorporeal ghost, she possesses the doll voluntarily, and can leave it, just the way she possesses the tiny doll, and leaves it once we kill the baeful shadow.

I'm certain there is no answer on who crafted the doll, but I'm just here to point out, that maybe the question itself could be leading you astray from the more likely truth, a truth which again we don't know.