This may be the most economical and efficient passive humidification system ever. The Humi-Care HX10 Crystal Gel Rectangle Humidifier contains specially formulated crystals that give off just the right amount of moisture to keep your cigars in optimal condition. They'll even re-absorb humidity if the level gets too high.
When charging the device for the first time. soak it in distilled water or PG solution until the gel expands to fill the inside of the unit. Subsequent refills won't require as much time as the initial soaking.