Design the stone before mixing the cement. Arrange the smooth rocks in the mold so you will have an idea of how you want the stones to look. Remove the rocks from the mold and set them aside so they are ready to use.
Lightly oil the inside of the cake pan so the cement will not stick. If you are using a stepping stone mold without a bottom, use a sheet of plastic underneath the mold or work on a level area of hard dirt.
Wear rubber gloves to mix the cement. Pour the dry cement into a dishpan or bucket. Stir it with a trowel to break up any clumps. Make a well in the middle of the dry cement. You will need about 7 pounds of dry cement for each medium-sized stone.
Add water, a little at a time, and mix until the cement is smooth and the texture is similar to a thick pudding or cookie batter. It is important to work quickly because the cement will begin to set within 10 minutes.
Fill the mold 1/3 full with the wet cement. Use the trowel to press out air bubbles. Repeat this process until the mold is filled with cement. When the final layer is in, use the trowel to press out remaining air bubbles and smooth the surface. When the surface of the cement takes on a wet, glossy appearance it is ready to set.
Press individual rocks into the wet cement. Make sure that each rock is pressed deep enough into the cement so that it will be held in place when the stone dries. The top of the rocks should be level with each other so that the finished stepping stone will have a uniform, smooth surface. It is not necessary to completely cover the entire surface with rocks. Leave a little bit of space in between the rocks. Work quickly because the cement will set within a few minutes.
Let the stone dry for 24 hours.
Gently clean the surface of the stepping stone using a toothbrush or soft cloth and soapy water to remove grime from the rocks. The cement is not completely set at this point. Take care to not damage the surface.
Let the stone dry for another 48 hours then remove it from the mold.