After you have the diagram, construct the product on the assembly station.
The Iron Wood Support (Diagram) is given when accepting said mission on Commission Board during the Mission: South Block Development.
Alternatively, the diagram can be bought from the Research Center Exchange for 14 .
The Iron Wood Support (Diagram) can be used to learn how to make Iron Wood Supports.
Iron Wood Support
2 Wooden Pillar
5 Iron Wooden Plank
2 Steel Frame