Bend the pipe cleaner into a shape, like a snowflake or heart. Make sure the shape can fit inside the jar without touching the sides, but don't leave the pipe cleaner in the jar yet.

Boil enough hot water to fill your jar. Pre-measure the capacity or check to see if it is labeled on the bottom of the jar.

Add two to three drops of food coloring to the boiling water. Any color is fine.

Pour boiling water into the jar, filling it nearly to the top, but leave a small space to account for water displacement when you put the pipe cleaner shape in.

Mix in three tablespoons of Borax for every cup of water in your jar. Do this one tablespoon at a time, and make sure everything is well blended.

Attach the pipe cleaner shape you made to a pencil with a piece of string. Submerge the pipe cleaner shape into the jar completely. Make sure it is hanging in the middle of the jar, and not touching the top, sides or bottom. The pencil should lay across the top of the jar, centered. Fasten it with a piece of tape, so it doesn't roll back and forth.

Sit the jar on a windowsill overnight and check on it in the morning: the pipe cleaner shape and the string it hangs on will be covered in crystals.