The stonemasons of the construction site of Guédelon learn and pass on the mastery of gestures. Their body adapts to the tools they use. Often they have a ball of 0.4 to 0.8 inches (one or two centimeters) that forms on the first phalanx of their little finger used as support for the chisel during the cutting of hard stones. The three middle fingers are tightened on the chisel, the thumb locks the ensemble, and the little finger is closed below the instrument it supports and whose strike it guides.