1. Draw a hollow circle with a light line. You can use a pair of compasses or trace a round object or circular template to get a clean circle.

2. Choose a light source for this sphere. The light source in this example is on the upper left, somewhat in front of the page (or behind the viewer).

3. Begin shading. Start opposite the light source and move inwards. The darkest area will be furthest from the light source. Create circles or part...

4. As you move towards the light source, fill the circle with less and less pressure, heavier on the dark area, lighter on the light area. You can...

5. Use your finger or a tortillon to blend the shading and add a shadow. Notice how the circle now appears spherical, with depth.