My old Sally wig was a bit of a disaster: cheap party wig forced into dreadlocks. That wig has been scrapped (and bits of it used to stuff some adorable purple owls), and I've made a new one.
This wig is made of three balls of yarn, sewn to a cap made from an old pair of tights. I made wefts out of the wool, and sewed them down the centre. I think I'm going to need more wool though, because when the wig is on, the yarn falls back and leave huge gaps where you can see the leopard spotted cap.
Apart from the bald spots, I'm quite satisfied with this experiment. I was thinking of creating a Rapunzel wig using the same method (it would save me a LOT of money)
When the wig is less bald, I'll post some better photos.
EDIT: I think I've solved the problem. I looked at some of my wigs, to sew the layout of the wefts. There's a section sewn down down the centre front, then the other wefts are sewn in horizontally. So I removed two of the wefts and sewed them on horizontally, and it worked like a treat: the wig looks much better. I also tacked down some of the wool on the front, to stop it from sliding back.
Here's the tacked down front section.
Here are the newly positioned wefts.
For anyone who is interested in making their own yarn wig, here are some tutorials.