Like most of you who pointed this out, I've heard time and time again that you must use Spanish Cedar.
However, the attached link would indicate that, although perhaps not ideal, the red cedar is probably okay.
http://www.humidor-guide.com/humidor-spanish-cedar-1-1.php3
I suppose for some the strong cedar character might even be a plus. Given the option, I think I would prefer not to chance it, but I think the humidor is beautiful, will probably perform just fine, and I'm envious. It's the sort of project I've been "planning" to do for years!!!
Nice work billyc.
Elrico