Grow crystals at home by dissolving a salt in hot water to make a saturated solution. Suspend a string in the solution and give the crystals time to grow. The crystals form on the string and become more visible as they grow.
Make home-grown crystals from granulated sugar or table salt. Sugar crystals are edible, but they take longer to make than crystals made from salt.
To prepare, tie one end of a piece of string to a pencil or butter knife. The other end of the string should hang low enough to reach the bottom of a clean glass jar without touching any of its surfaces.
Bring 1 cup of water to a boil in a separate pan. Add 3 cups of salt or sugar to the water, one spoonful at a time. Stir the solution until to all of the salt dissolves. Any undissolved salt remaining at the bottom of the pan causes the crystals to form on the undissolved salt rather than form on the string. At this point, add a few drops of food coloring if you prefer colored crystals.
Carefully pour the salt solution into the glass jar and suspend the string in the solution. Cover the jar with a paper towel or coffee filter and store it in a clean, cool place to allow the crystals to form. When the crystals have grown to the desired size, remove them from the solution and dry them so they are ready for use.