As previously stated the box needs to be of a wood that can remain stable in high humidity conditions, although it can be protected from the inside humidity with a thin veneer of Spanish Cedar over a sanding sealer, if you are careful to cover every square inch on the interior and seal corners with an odorless low VOC sealer. Certain woods will draw the humidity out of your humidor like Pine or Poplar or any "soft woods" so it's better to use a box made from some kind of "hardwood". I have boxes of Cherry and Maple and have seen humidors of Oak, Bubinga, Zebra Wood, Mahogany, & Ebony, and they do just fine. If you need Spanish cedar veneers let me know as I usually have plenty kicking around. (we use them as a lining in our cans we ship in.) Most important is the seal on the lid which needs to be very good, but there are ways to achieve this with other products like weather seals or rubber/silicon gaskets~!