When drawing something with left/right symmetry you can duplicate and then horizontally reflect layers to get the desired effect.
As a good example of left/right symmetry we have drawn a butterfly wing. Let’s make it symmetrical.
Tap (1) Duplicate Layer in the Layer Window.
Tap (1) Move Layer in the Layer Window.
Use (1) one finger to drag and (2) two fingers (pinch) to enlarge or reduce, so that both wings can fit on the canvas. When you are finished tap (3) Done.
Tap (1) Invert Layer Horizontally in the Layer Window.
Adjust the position and size of the reflected layer with the Move Layer command.
Apply color and sign your work to finish it off.