So after thinking long and hard about what in my stash might appeal to her (she's 3 and has strong opinions about everything), I thought some kind of purple-ness was a safe bet. And some fuschia mohair for the tutu part. I'm super excited to see how this Malabrigo Rios colorway knits up: it's called Lotus and it's got purple and aqua, which is so pretty.
I will have to modify the back to get rid of the button closure; my daughter has a strict no button rule (don't ask). So I think 2 I-cord ties should do the trick.