For a similar surface area I think you could just fill your bathtub to an inch deep and wait for it to evaporate. You'll wait a long time, and your bathtub will get gross, just like this object will.
And with the point being power-free, the air is going to be static or nearly so around the object (or bathtub). If it's supposed to get a boost from moving air from a forced-air furnace, that's cheating -- because in that case you could just install a similarly passive flow-through humidifier on that same furnace and be done with it, save perhaps an annual pad change. Many use no power, just the same "capillary and evaporation" as this - except with actual calculations underlying their specifications.
And with the point being power-free, the air is going to be static or nearly so around the object (or bathtub). If it's supposed to get a boost from moving air from a forced-air furnace, that's cheating -- because in that case you could just install a similarly passive flow-through humidifier on that same furnace and be done with it, save perhaps an annual pad change. Many use no power, just the same "capillary and evaporation" as this - except with actual calculations underlying their specifications.