Put on your gloves. Cut two fluorescent markers in half. Remove the felt inserts and place them in a bowl with 3 1/3 ounces of water. Let them soak for 15 minutes. Squeeze any remaining ink from the felt into the water.

Pour the mixture into a glass jar. Add two grams of alum to the fluorescent water. Stir it until the alum dissolves.

Pour a small amount of the saturated solution into a Petri dish. Put the lid on the jar. Allow the jar to sit in a warm place overnight. The solution will form crystals. Choose the largest crystal to be your "seed." Tie the seed crystal to a thin piece of cotton thread.

Pour the rest of the solution into a clean jar. Tie the other end of the string to a pencil. Without touching the sides or bottom of the new jar, lower the string with your seed crystal into the solution. Rest the pencil on top of the jar. Set the jar aside for several days. As the solution evaporates, you will see more crystals forming. The seed crystal will grow larger.

Grow a giant alum crystal. Leave the crystal in the solution for an extended period of time. Replenish the alum solution as it evaporates.

Check your crystals. Set them under a black light. A successful experiment produces glowing crystals.