Search the Internet or visit the library to find images of Chinese ink stones to inspire your design. You may use a sketchpad to design your "stone," or simply develop a mental picture of what you'd like the finished product to look like.
Use rolling pin or hands to form clay into shape of the stone you designed. Include a depression deep enough for ink to settle without spilling over edges.
Use a toothpick or carving knife to create designs in your stone. You may consult images or improvise for personalized look.
Bake clay according to directions on package. This will harden your stone. Allow to cool.
Use polymer clay varnish to varnish your stone. Allow varnish to dry according to directions on package.
You may also find a stone in nature. Go to a park, forest or beach to search for stones with natural dents deep enough to hold ink. Select one you love. Test it to be certain it lies flat and will not allow ink to spill.