Things You'll Need
Instructions
Fill the container you chose to use halfway with sand. Any type of sand will do, but it is best to start out with coarse sand, as it speeds up the smoothing process.
Fill two-thirds of the container with water.
Mix the water and sand together. You'll use this mixture, called "grit," to smooth and polish the rocks.
Add the rocks to the grit mixture and cover the container with the lid. If you don't have the original lid, use any lid of a similar size and duct tape it down so it isn't loose. Use about two handfuls of rocks if the container is the size a 11.5 ounce coffee tin.
Shake the tumbler in all directions frequently over the next several days.