Take your pipe cleaner and shape it to the desired shape of your finished crystal. The crystals will be clear so you will see the color of the pipe cleaner when finished. Choose your color carefully.
Heat your water to boiling. You can make a bigger batch than listed, just remember to increase the borax accordingly for the amount of water used. Add about 3-4 Tbsp of Borax for every cup of water in your solution. Stir until the Borax dissolves in the water. You want the water to be clear because if the water gets cloudy then your crystals will be cloudy.
Once your solution is mixed, pour into the mason jars about three quarters of the way to the top.Use the string to tie your pipe cleaners to the popsicle stick ( or you can use a pencil). Then place these sticks over the rim of each jar so that the pipe cleaners are suspended in the water.
The submerged pipe cleaners should form crystals over the next 12-24 hours.The longer that you leave them then the bigger they will grow.
The crystals should have grown around the colored pipe cleaner. Now, simply take them out of the jars and let them dry and enjoy!
Notes
Be sure that none of the pipe cleaners are touching each other or the sides of the jars so that they can grow as large as possible.