Cut out a shape like this. it should fit around your finger.
Step 2
Fold.
Step 3
Sew. You couldn't see the thread in this pic, so I drew the line on where you should sew. XD
Step 4
Turn inside out and give it a face with a marker :D I often give them :D faces, but I also got one with a :) face, and this one has a D: face, because the dolls with a :D face are going to molest her! :D
Step 5
Cut out the hair. One back, one front. If you have difficulties with cutting the hair in the right shape, contact me, and I'll make a suiting pattern for you :]
And good luck with the cosplay!