I’m here to say have would you implement a system where you build your room/building out building blocks/modules (if have heard and used Modular Building System Plugin & probuilder) but how would you build the room out of cuboid components like in NMS. so is there a way to modify a cube at runtime which is hollow (inverted and also has a second cube for the external view)
Instead you have a cube composed out of pieces - floor plate, ceiling plate, and wall plates. When you “extend” a wall, you simply place another cube (composed out of objeccts), and remove walls in the area where cubes are connected.
Alternatively, if the construction is more complicated, you could replace the existing piece with a different one so that there is an opening between it and the new piece and any other pieces it’s touching.
If you didn’t want to get that complicated, you could leave it up to the user to place the pieces they wanted, with the holes they wanted. This would even let them build more complex structures with internal dividers.