Mirroring a 3D Object Across the Working Plane To mirror a 3D object across the working plane: 1. Select the 3D object to mirror. 2. Click the Mirror tool from the Basic palette, and then select Mirror or Duplicate and Mirror from the Tool bar, depending on whether the original object is to remain in place. 3. Select Mirror Across Working Plane mode. The object or its duplicate is mirrored to the opposite side of the working plane. There is no need to create an axis line.