From FreeCAD Documentation
- There are several ways to invoke the command:
- Press the Beam cross section button.
- Select the Model → Element Geometry → Beam cross section option from the menu.
- Choose the type of cross section and specify the necessary dimensions:
- Rectangular: width and height,
- Circular: diameter,
- Pipe: outer diameter and thickness.
- Optionally, press the Add button in the task panel and then click on the edge you want to have a prescribed cross section. If the edge selection is free, all remaining edges (whose cross section is not defined by other FEM ElementGeometry1D objects) will be automatically assigned.