The human anatomy is a fascinating subject for sculptors. Look at ancient life-size stone sculptures to appreciate the complexity of the human form and how difficult it must be to get the proportions just right. Fortunately, working in wet clay is much more forgiving than stone as it allows you to add material if you have removed too much. With something as complicated as a human hand, it may take some practice and time to get it right. A successfully completed sculpture of a hand in clay is a powerful art object.
Find some good images of hands. Select an image showing a hand lying on a flat surface as your main reference. Gather images to show the hand from various angles to show you areas that might be hidden in other images. Place the hand images near your sculpting area so that you can easily refer to them as you sculpt. Use your own hand as a model as well to help you.
Knead about two pounds of clay like bread dough until it has a good working consistency. Make a large ball out of the clay and place it on the table. Flatten one side, tapering gradually, to the thickness of about one inch. Leave the other side twice as thick, as this will be the side going up to the wrist. Make the sculpture end just before the wrist to focus on the hand itself. Shape the back and sides of the hand as it tapers toward the wrist.
Carve out the sections in between the fingers with the knife. Make three smaller channels and a larger section between the forefinger and thumb. Measure and mark the ends of the fingers with a needle tool. Cut off the ends and continue detailing the finger separations until all five fingers look proportionally correct. Shape the thumb positioned almost on its side as the hand lies flat on the table.
Etch the fold of skin where the thumb meets the hand and where the joints are located on the underside of the forefinger, thumb and little finger. Carve into the underside of the fingertips to create realistic curved finger-ends, including the thumb. Carefully wipe a damp sponge to clean up any tool marks on the sides and the visible underside of the hand are finished.
Carve out the fingernails using the knife by removing a thin layer the size of the nails. Etch in a line underneath the end and on the sides of each fingernail to define them. Note that the angle of the thumbnail is offset slightly from the other fingers. Use a damp sponge to make the surface of the nails very smooth. Continue detailing by etching in the lines on the fingers at each joint. Examine the reference images if you get confused.
Detail the knuckles and veins on the back of the hand. Form the lines going from the knuckles toward the wrist. Keep detailing and periodically using the damp sponge to soften sharp lines and to remove tool marks. Double check that the sides of the hand are naturally curved. Note how the palm of the hand curves out slightly on the side below the little finger.
Look at the sculpture from all angles to check the proportions. Make any necessary alterations or corrections before the clay dries.