Char cloth can be stored in the Altoids tin that it was made in. Odds are if you’re using this for personal use then you won’t need to make much more than what’s in the tin for a long time. You don’t need a large amount of char cloth to start a fire. Keep the char cloth away from water and try not to let it near a large fire as it could catch. Otherwise char cloth has a long shelf life and it has no maintenance requirements for long-term storage.