To Create a Drop-Down List for a Component Property (AutoCAD Mechanical Toolset)

At the Command prompt, enter AMOPTIONS.
In the Options dialog box, select the AM:Standards tab.
In the Standard Elements list, double-click BOM. The BOM Settings dialog box is displayed.
In the Available component properties list, in the row corresponding to the component property you want to edit, click in the value column. The button appears.
Click . The Expression Builder dialog box is displayed.
In the Select value type list, select Predefined list.
To add an entry to the user-defined list:
1. Click New. The program adds a row to the Predefined List.
2. In the new row, click the value column and enter a valid value for the component property.
3. Click the Description column and enter a short description.
Click Move up or Move down to display the new row in the correct position
Repeat Steps 7 and 8 as required.
Click the row to set as the default selection for that property and click Set Default.
Click OK until all dialog boxes close.