In my Flock Your Cornrows post I said you could use flexible modeling paste to hide the rooting holes in a dolls head. However, you can also use it to fashion hair and close the lips of a smiling doll.
If you just wanted to cover rooting holes you could smooth the paste over the head with your finger (I always use gloves) or scrape it on with a metal or plastic palette knife. If you want a crisp hair line then use masking tape to define the areas you don't want affected and remove the tape immediately after applying your paste.
For my purposes I've used my palette knife to pat on a thin layer of paste and let it dry for about 30 minutes. I didn't smooth it because I wanted a tacky layer for the next one to adhere to. I'm going for an afro-centric look, so the more texture the better.
My second coat is thicker and I'm more uniform in the peaks and pulls that I'm making with the paste. I also added a layer to the lip opening, let it dry 15 minutes and then applied a second coat that I shaped into a closed mouth.
Once the paste hardened completely (about 4 hours in the humidity of Florida), I applied a single layer of black paint. You could now put on some glue and flock for a cool effect but I'm leaving mine alone.
I've actually built lips on top of her existing ones, covering them completely. I used a tooth pick to make the crease in her mouth while the paste was still pliable. Not all dolls have such wide open smiles as Nikki does so you can get away with simply filling the opening. However, I wanted to show you the possibilities.
I sanded the bottom lip to make it smooth, but left the top one rough so you can see the difference for those of you who want to make some Jolie type lips. I filled the entire cavity of her mouth, side to side, but you don't have to.
A special note:
This will be the last procedure that my hardworking practice model will undergo. She is officially retired. A complete trooper through so many faces, applications and experiments, she will now be enjoying her dolldom test free. Thank you for your service, Nikki No. 3, thank you.