A mahlstick, or maulstick, is a stick with a soft leather or padded head used by painters to support the hand holding the paintbrush. The word derives from the Dutch maalstok 'painter's stick', from malen 'to paint'.
In 16th- through 19th-century paintings of artists, including self-portraits, the maulstick is often depicted as part of the painter's equipment.
William-Adolphe Bouguereau holding painting implements
Self portrait of Caterina van Hemessen
Self-portrait by Sofonisba Anguissola
Detail of Vermeer's Art of Painting with artist using mahlstick