Some open thought @ClockworkOcean :
You told something about object-oriented framework. So would it make sense to create each stone as a separate blueprint or having all stones ready inside of a blueprint as existing actor-meshes? If yes, how can I give these objects/meshes a unique ID then? Maybe its simpler by end of the day to make the layout directly inside of a BP with existing meshes, but then have to define which ones are pairs.