Pick two containers. You want something that is not very porous, such as ceramic, glass or Pyrex, and the containers should be similar in size and shape. Long, narrow containers will produce a more dramatic display. Clear containers make the process much more visible, and therefore more fun to watch!
Many household products can be used to make crystals. One of the best ways to get almost instant results requires Epsom salts (also known as magnesium sulfate). Look in the pharmacy section of your local store if you don't have any on hand.
Prepare one container by combining ½ cup of Epsom salts with an equal amount of very hot tap water. Be sure not to boil the water.
With a clean spoon, stir the solution for approximately one minute. This is your growing solution. Be sure to leave some intact crystals in your container, as they are the building blocks of future crystal formation.
Place the container with the growing solution in the refrigerator to chill, along with a second, empty bowl. The second bowl will be used to create a beautiful tower of crystals later on. To ensure easy removal, place heavy, round weighted base materials in the bottom of the container. Poker chips, metal washers, or broken terracotta are good options. This will also make an interesting display piece when finished.
Remove the newly formed crystals. Within two to three hours, very fine crystals will have formed in the growing solution. Once this has happened, gently remove the crystals from the growing solution with a clean utensil.
Place the mound of crystals in the second chilled bowl. Use caution, as the base crystals will be extremely delicate.
Pour the rest of the growing solution into the bowl. Be very careful not to let any undissolved crystals get into the bowl. This will disrupt a solid crystal formation.
Let the bowl sit out at room temperature. Within three hours, there should be a tall crystal mound ready for display.