Another classic Petey, looks real nice!
I've read a lot about the construction of humidors and mentioned often was to seal the interior (shellac/lacquer) behind the cedar to prevent moisture migration, but I can't imagine anything getting through hard/dense woods like that.
Biggest problem I have is locating the gauges. The digital ones I use are ideal for punching a hole through the top and being able to read the status from the outside, but having an "ugly" gauge messing up a fine wood lid is just insane.
You do great builds, design, construction, and woods are awesome!