I've made a simple one inch wide band and temporarily attach it to the mask to see how the beak will sit on the face.
That will basically work, but I need a nicer way to attach it, and I need a strap running over the head (front to back) to keep the beak cantilevered and off of the chin. Here I've added tabs to the leather mask to accomplish both things.
I've decided to make this mask white (a classical plague doctor mask color), and so I paint it with acrylic latex paint. I also finish the eye and beak hardware and attach them to the mask.