Tricia Roush is justifiably excited by her acquisition of an 1821 Conformateur in excellent shape. Conformateurs are Victorian devices used to measure the irregularities in the heads of milliner's customers, to ensure a better fit from the eventual hat. Roush explains the device's working in detail, with generous photos of the extraordinary device in action.
While the conformateur is on the head, after the fingers are pressed in so that they are conforming to the head shape, a piece of paper is placed into a frame on the top of the machine. Little pins stick out of the top of the machine, each one attached to one of the fingers, so that the pins now reflect the head shape as well, but in miniature. The frame swings down on a hinge to press the paper into the pins, perforating the paper. In this photo, you can see that the inside of the frame is lined in cork, and there are little holes in the cork where the pins have pressed.
The perforations in the paper make a pattern that's a recording of the person's head shape. The hat maker then cuts the pattern out with scissors along the perforations to store for future use. Here are some examples of the paper patterns. Because it's a shrunken version of the person's head shape, any bumps and asymmetry in the head shape (we all have them) are exaggerated in the pattern, as you can see here.