Paul,
Very nice. I like the idea of the small sections to make them easy to lift and you only need to open what you need.
I would suggest you add some type of built in handles for each section to lift the sections.
I know you can have a separate tool for lift the sections, but permanently attached handles means that Kathryn will not be mad at you for losing them when you need for her to open the pit nor will she drop them on your head.
