3D Print of Shattered Galaxy - Core

It's mostly the same as the slots on any other wall - after you place a platform on top, clip-on accessories like ladders, railings etc. can connect to these ports. That said, these modules have two sets of ports at the bottom and one set on top, allowing you to transition from a larger platform (e.g. 3x3) to a one that's smaller in one direction (e.g. 2x3) within one floor, like on the attached pic.