How deep does the container tree extend? In other words, is there a limit to how many containers you can put in other containers?

There's no limit to how many containers can be nested inside each other. The solar system is built out of a root container, so we've got the Stanton system container. And then inside that, there's a container for each of the planets, I believe. And the planets themselves contain object containers for the moons and the space stations and the planet itself. And then on those, like for Grim HEX, there'll be the Grim HEX object container, and then inside Grim HEX there'll be object containers for the different shops. So I think we're probably getting on to about seven levels deep. But in theory, there's no limit.