I just got back from a trip with my 15 ct Otterbox Cigar Caddy. That thing kept an incredible seal with pressure change and I had to use a key to get it open.

But regardless of my praise of this thing, I use the Boveda humidipak to hold the RH. Those things work well, and in such a small space, can never fail. Otherwise you could always put some heartfelt beads in a small baggie or something.