Two functions, "Symmetric editing" and "Mirroring", are provided as the methods to create bilateral symmetric objects which are very effective in making like characters.
Symmetric editing becomes effective when you press the [Sym] button in the edit option group on command panel.
Be sure to know that this symmetric editing does not create the other side of the object in real time. When you operate with some command like [Create] [Move] [Scale] [Rotate] [Magnet], it searches the pairs of vertices or faces selected on the spot and it gives operations to the pair at the same time. It takes time to process when the number of vertices are large because it tries to find pairs on the occasion.
When [Sym] button is being pressed, the unsymmetrical object which does not have pair vertices becomes destroyed if it is moved. This is the function to make the unsymmetrical point fixed at 0 point in the X direction. By using this, you can easily arrange the vertex at the center of the boundary of symmetry.
The mirrored face is shown in real time by selecting mirroring in the dialogue of object property. This means that only one side is saved in data and both sides are only shown when it is displayed. As only one side is saved in data, symmetry is maintained for all commands without fail. You can make the other side of the datum with menu [Object] [Freeze] and it is usually frozen automatically when you export it in the files other than MQO.
Commands like [UVedit] [Primitive] [Twist] [Bend] [Shear] [Lattice] [Knife-Cut straight faces] [Weight] [Vertex color] are not available with symmetric editing.