Gamera
I'd love to see how you work up the whole 'cakebox' idea.
Well, as is very common with KSP, the unplanned vehicle disassemblies occasionally steer towards a different answer that one started with.
I have the game mod which supports LaGrangian points in the Kerbal-Mun sytem (ok, I'm a geek, I like the gravity reactions you get). So, since I can get wdeges into orbit, I can tow them to the lagrange points and build up a gravity-stable 3km round "space station" of sorts. So, I've managed to wander off into sketching designs that let sunlight in and also create diurnal cycles (biomes need those).
Which is leaning toward a "U" shape with a glass lid formed into a hoop. The glazed side can face the sun, and the bottom of the hoop will provide a natural twilight and night. Now I just have to cipher out what 1 rpd diameter gives at least 0.6G that also allows 150m depth.
Oh well.
I'm going to go plug my copy of Once Were Giants in the bluray, as a movie with a beginning, middle, and end is very appealing right now.