(The links embedded below are select entries from the full verbosity build blog.)
After building rev A and learning a lot about acrylic construction, I proceeded to start designing rev B. There were problems with rev A that I wanted to fix, and some additional objectives beyond that. I decided to give up trying to emulate the Apple PowerMac G4 cube and design a different airflow scheme. Some of the lessons aren't even part of the final product: I designed construction fixtures to make assembly easier.
For the moment, revision B works well for the enclosure. It has been working well enough that I haven't had to worry about the hardware. It frees up time for learning the software side of running FreeNAS on my home network.