What's the best way to make a building system bp?

I saw this: - YouTube

I asked him about it and he told me it was done in C++, but I want to implement something like this in blueprints.

How can something like this be done?

I figured out how to make placeable foundations, but I don’t know how to make them snap to each other.

Also, I don’t know how I would make pillars/walls snap to the foundations, and then doors snap to doorframes etc.

Would this be done with bones and sockets or collision boxes?