1. Open SAI2 software and create a new canvas.
2. Select Edit in the menu bar, and then click Preferences.
3. In the preferences window, locate and click Technology Preview.
4. A butterfly-like icon will appear. Click this icon and select "Vertical Symmetry".
5. Go back to the canvas and use the brush tool to draw on the canvas. All the pictures will be along the symmetry axis.
6. In addition, the symmetry axis can be opened by constructing a new symmetry scale. The specific operation steps are as follows:
7. Click the "New Symmetrical Scale" menu option in the laminate on the canvas.
8. At this time, a vertical symmetry line will appear on the canvas.
9. The content drawn on the symmetrical ruler will automatically present a symmetrical effect.