Select the custom wall and navigate to the properties panel that opens up.

Navigate to and open the Wall Thickness/Composites dropdown menu.

Therein, navigate to Wall Hatching Options.

You can customize the type of hatch, stroke color, fill color and scale therein.

To create a composite with hatch, select the Materials Icon in the Global preferences and Setting bar, and in the panel that opens up, select Composites.

In the window that opens up, select the Clone icon to make a clone of any of the composites existing in the design. Enter the Desired value into the Thickness field of that cloned copy.

To assign a hatch, click on the 2D Hatching square under the Material & Hatching column. In the Hatching Patterns window that opens, specify the type of hatch, stroke color, fill color and scale therein and select Apply to save changes.

Once all the properties of the new composite is set, select Apply to load it into the design.

Select the composite wall to which you wish to assign the hatch and navigate to the properties panel that opens up.

Navigate to and open the Wall Thickness/Composites dropdown menu.

Select Composte under Thickness Source, and from the corresponding dropdown menu, select the new composite to assign it to the wall.