Mirror Entities
General Capabilities
Applies to 2D sketches and 2D
sketches created on 3D
sketch planes.
Mirror
to only include the new entity, or both the original and the mirrored
entity.
Mirror
some or all of the sketch entities.
Mirror
about any type of line, not just a construction line.
Mirror
about edges in a drawing, part, or assembly.
When you create mirrored entities, the SolidWorks software applies a
symmetric relation between each corresponding pair of sketch points (the
ends of mirrored lines, the centers of arcs, and so on). If you change
a mirrored entity, its mirror image also changes.
Conditions for 2D
Sketches on 3D Sketch Planes
To
mirror existing sketch entities:
In an open sketch, click Mirror
Entities 
(Sketch toolbar) or Tools,
Sketch Tools, Mirror.
In the
PropertyManager:
Select
sketch entities for Entities to Mirror
.
Clear
Copy to add a mirror copy of the
selected entities and remove the original sketch entities.
- or -
Select Copy
to include both the mirrored copy and the original sketch entities.
Select
an edge or a line to Mirror about
.
Click OK 
.
To
mirror sketch entities as you sketch them:
Select
a line or a model edge in an open sketch.
Click Dynamic Mirror
Entities 
(Sketch toolbar) or Tools,
Sketch Tools, Dynamic
Mirror.
Symmetry symbols appear at both ends of the
line or edge.
Create
the sketch entities that you want to mirror. The entities are mirrored
as you sketch them.
To turn
mirroring off, click Dynamic Mirror Entities again.