3D tile based map editor

I am trying to make a game where at the start of each round, one player creates the map by connecting different rooms and hallways, and honestly I dont even know where to start. I have made a couple of different rooms in blender, and my plan was to set different connector points on each mesh so that they would snap together when creating the map, but nothing I have tried so far has worked. any advice on how to get a system like this working would be greatly appreciated. Thanks in advance.