Mix ground chicken, egg, breadcrumbs, 1/4 teaspoon salt together in a bowl. Pinch of about 2 tablespoons measure and shape them into balls and place on a plate (a 2-tablespoon measure ice cream scoop comes handy). Place a small of water right next to you, dip your hands in the water before you shape each ball. This helps not to stick to your hands.
(You could add about 2 tablespoons of additional breadcrumbs if it is difficult to shape meatballs, but they might not be as tender)