Symmetry
This command makes a mirror image of the selected objects. With this command you can do a:
- Central symmetry 
- Axial symmetry 
- Planar symmetry 
Requirements
Select the object(s) to be mirrored and launch the command.
- Choose the symmetry type. The corresponding buttons are automatically displayed. 
- Define the position of a point for all 3 symmetries. 
- Define the axis direction for the axis and planar symmetries. 
- Select whether Create copy is needed or not. 
- Optionally, you can Preview to see if the result is correct. 
- Validate the command with OK, or, close the dialog box with Cancel.