I want to make sure that since I am going to the trouble that it's perfect.

First off, what is the absolute ideal size and shape for a BP? Obviously floor space is more important than height and you neither want to be too big or two small. What else should I consider?

I plan to make essentially a box that loads from the front and a "tray" that will actually be the floor of the enclosure. The tray will be made from wood, Bondo and glass and be removeable for easy cleaning. The wood will be the frame, the glass will be so I have the option of using an under tank heater if I think it's necessary. The Bondo will make it water tight and easy to just hose down. It'll be capable of holding substrate. How deep should I make it?

The front door will be cabinet style with a Lexan window (not too big so that he feels as secure as possible). The top will also swing open for easy maintenance of overhead lighting. The lighting will be screened off from the living area, of course.

Obviously aesthetics are important to me otherwise I'd go with the proven tub method. That being said, I plan to paint the interior with an epoxy paint, probably a simple pattern that gives the look of tall grass (basically vertical stripes in two or more natural green colors).

What else should I consider?