Blender Basics · scottaferguson.org

Lesson 7: Mirror modifier

About 14 minutes · Blender 5.2.1 LTS · Mac Mini + Magic Mouse

What Mirror does

Most real objects are symmetric, like a mug, a helmet, or a logo shape. The Mirror modifier copies your geometry across an axis, so you only model one half. A modifier is a setting that changes the object without changing the original mesh. You can turn it off or change it at any time.

Real screenshot from the Blender manual Mirror modifier panel with the X axis button highlighted in blue
What to look at: the Axis row. X is highlighted in blue, which means the copy is made across the X axis. That is the default you will use in this lesson.

Image: Blender Manual by the Blender Documentation Team, licensed under CC BY-SA 4.0. Shared unchanged.

Steps

  1. Tool Add a cube: press Shift + A, then Mesh > Cube. menu path unverified in 5.2.1
  2. Key Press Tab for Edit Mode, then 1 for vertex select.
  3. Mouse Rotate the view with Cmd + drag until the left side of the cube faces you. Hold the left mouse button on empty space and drag a box around the four corners on that side. Release.
  4. Key Press X and choose Vertices. The left side is gone. the delete menu label is unverified in 5.2.1
  5. Key Press Tab to return to Object Mode.
  6. Menu In the Properties panel, click the blue wrench tab (Modifiers). Click Add Modifier, then Generate > Mirror. The button is at the top of the Modifiers tab, per the manual.
  7. Check A full cube appears again, with both sides matching. The Axis X button is blue.
  8. Key Press Tab for Edit Mode. Click a corner on the right side, press G, and move it. Click to confirm.
  9. Check The left side moved too. Blender copied your change across the middle.
Why the cube looks cut in half at first: the mirror copies only the geometry that exists. Your remaining half is copied to the other side. The Merge setting joins the seam in the middle.

Project: mirror block

A symmetric block made from one half. Start from a new cube, delete one side, and mirror it. Save as mirror-block.blend.

Finished: two matching halves, one mirror line
Finished product: the dashed line is the mirror plane. Both sides match because the modifier copied one side.