I made several more changes. The biggest was that I removed the eye sockets from the base model. They were left over from previous masks that had externally-installed eyes, and were no longer necessary. I retained them so I could see the position of the eyes, but they were not easy to adjust since they were made up of several curves, and they also affected the shape of the area around them and made it harder to adjust. The eye shape is now solely defined by the cutter, which is a lot easier to adjust (I am also using it to show the position of the eyes on the NURBS model).
I also moved the inside of the cheeks upwards, moved the nose and mouth forwards a bit, made the nose more rounded, and
softened the lips a little. In addition, I changed the back edge of the scalp so that it is defined by multiple curves in a similar way to that of the rest of the mask (before, it was defined by a single curve, making it sharper than it should be, and leaving a long thin hole in the model, which sometimes caused mesh repair programs to repair it incorrectly).
Here's what the original NURBS model now looks like in Ayam. I have a mirrored copy of the eye cutter for the other side, but I have it hidden here to show what that area looks like without it.
