Create and modify 3D models > Create 2D geometry > Set a mirror for 2D geometrical elements
  
Set a mirror for 2D geometrical elements
When you create 2D geometrical elements such as lines, arcs, rectangles, slots, or circles, you can use the Set Mirror command to set an existing line as a mirror or select two points on the workplane to set the line which connects the two points as a mirror.
To set a mirror,
1. Click Modeling and then, in the Draw group, click one of the following buttons:
Line/Arc
Rectangle
Circle
Arc
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You can also click the arrow next to the above buttons for additional buttons.
2. Right-click a workplane and choose Set Mirror on the context menu, or press SPACEBAR and click on the Option Mini Toolbar (OMT).
3. To set a mirror,
Select two points on a workplane or in the viewport to set the line which connects the two points as the mirror or,
Click two points on a line to set the line as the mirror.
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Press SPACEBAR and click on the OMT to set another line as the mirror.
Press SPACEBAR and click on the OMT to toggle the mirror ON or OFF.
4. Create the required geometrical elements on the workplane. The geometrical elements are mirrored on the opposite side of the set mirror.