A perfect makeshift travel humidor is to take either a Nalgene bottle, or any 32oz. PowerAde/Gatorade bottle. Make sure they're clean, then cut out a piece of anti-static computer packaging (I always have some laying around being a techie), and wrap the packaging around some recycled napkins that have been soaked and squeezed with distilled water. The literal packaging could really be whatever you want, but for a space saving humidifying 'thingy' the wrapped recycled napkins are great. They have to be recycled napkins because they're denser than regular napkins and don't break apart easily when wet.

Anyway, just a thought.