A tool on the Unity Asset Store: assetstore.unity3d.com/en/#!/content/31548
Specify an area or line and it will assemble a fully destructible tower, scaffold or fence out of modular pieces.
• Builds scaffolds, towers and fences out of modular pieces
• You can decide the arrangement of the pieces manually, or randomise their arrangement for variety.
• The structure is fully destructible.
• Automatically changes LOD (Level of Detail) according to camera distance