A rock tumbler is a device used to polish small rocks until they are completely smooth. The tumbling method emulates the process by which rocks turn smooth naturally, which is by being washed in rivers or the ocean or naturally ground and smoothed by other rocks or small particles. Rock tumblers can be motorized or operated by hand. They are easy to make and easy to operate. With just a small amount of effort you can create beautifully polished rocks that can be used in a variety of artistic crafts.
Fill the cylindrical-shaped container with sand until it's half full. Use coarse sand to begin the process.
Pour cold water into the container until the container is two-thirds full. Put the lid on the container, making sure the lid is watertight. If the lid is loose, then use tape to secure it so no water can leak out. Shake or swirl the water and sand together until thoroughly mixed. This mixture is known as grit.
Take off the lid. Put the rocks you want to tumble into the container. Replace the lid.
Place the container on the piece of wood so it won't damage your table. Roll the container backward and forward along the wood with your hand to ensure even movement. Pick up the container and shake it in all directions.
Repeat the process of rolling and shaking the container on a regular basis for several days. After one week remove lid from the container and examine the rocks. The rocks should be smoother than when you started.
Remove rocks from the container and pour out the mixture of water and sand (outdoors is fine). Replace with similar quantities of water and fine sand. The fine sand will produce an even smoother surface on the rocks. Place the rocks in the new mixture. Reseal the lid on the jar.
Roll the container back and forth on the wood and shake it in the same manner as before, as frequently as possible. Open the container and check the condition of the rocks every few days. The rocks should be perfectly smooth in about four weeks from the beginning of the process.