to purchase the amazing crystals you should go a sporting goods / outdoor gear store. the amazing crystals are found inside the hand-warmers but only the re-usable kind you can make your own amazing crystals instead in a large pot mix white vinegar and baking soda; the ratio is one tablespoon of baking soda to every cup of vinegar instead of measuring you can just taste. vinegar tastes like vinegar, and baking soda tastes like baking soda, but sodium acetate--the amazing crystals--are flavorless when the reaction has occured, and there is no more fizzing or bubbling, it is time to turn on the heat. boil the solution for a good, long while: untill the water is almost completely gone as the sludge at the bottom cools, you will observe crystals forming. these are the amazing crystals, but they are dirty! to clean them, simply rinse them off with 70% isopropyl alcohol, or with ethanol ... https://www.youtube.com/watch?v=PiFty9Oj0Gg

... https://www.youtube.com/watch?v=jeSQC5vmLPI