How to make in-game level building?

Hi.

How to make in-game building, like in

or like in Sims 3, Sims 4 building mode - http://www.youtube.com/watch?v=PBHjYFcdTnU ?

And players of the game must have possibility to build it’s own houses, doors, windows, to place furniture and etc…

As I unterstood, to solve this task I need to spawn some furniture and build walls like in 1.2 - Automatic Wall | Unreal Engine Documentation tutorial (from first position, clicked by mouse to second position, clicked by mouse).

It’s good and clear to understand.

Yeah! But!

How to save all spawned objects - walls, windows, door, furnuture and etc in SaveGame?

I have a assumption, that I need to get set (array) of the scene objects and iterate through it and save position and type of each object in SaveGame… But how to build such Blueprint?

BP for saving: