GM's Note - this is a Spoiler so avoid if you wish to.

Why the PCs can't analyze the rings, platforms, domes and so on.

They are not made of any material per se. Nothing physical could withstand the forces involved. They are made of warped space itself. Space folded again and again like some weird einteinian origami to create the effect desired. The texure is all microbumps in the surface of warped space.

That's all I have right now.