Build multiple Placeholders ( Game Objects ) at mouse clicks (X, Y) location. This placeholder should stick to the actual Wall, whose 3D map is being created in real-time. The mesh of the actual 3D world is being generated by a script already, you have to make sure, this placement anchor is generated as multiple game objects and scripts can be added to them. The scripts for the Mesh are already Made, You have to make multiple anchors in the real world.