Children develop the muscular control and concentration to master some precise hand and finger movements during their fourth year of life. Most can manipulate scissors with some dexterity and play enthusiastically with craft materials such as clay, paint, and crayons.
Shelov, S. P. (Editor-in-Chief). (2004.) Caring for Your Baby and Young Child: Birth to Age 5. The American Association of Pediatrics. Revised edition. New York: Bantam Books.