[Blender] What to do when you cannot mirror when adding bones (rigging)

Worries

So, after trying various things on my own, I found a way to mirror the bones on the x-axis.
Rigging becomes easier by making the bones mirrored (symmetrical).
When you move your right hand, your left hand will also move.
This time, I will show you how to mirror bones in Blender.

How to mirror bones

1. Align the 3D model around the z-axis.

1. Generate the rig.

I want to easily convert it into a Humanoid using Unity, so I use Rig for VRC to generate the rig.
Select Add [Shift + A] → [Armature] → [VRC_Humanoid_Rig].
([Object] → [Add] → [Armature] is also OK)

2. [Edit mode], select all the rigs, and turn on the right toolbar [Tools] → [Options] → [X-axis mirror].

3. The mirror is now complete. If you move one, the other will also move.

What happens if you mirror it later?

During editing, I checked what would happen if I turned the X-axis mirror on and off when I wanted to change the asymmetrical 3D model and rigged it later.

First, continuing from earlier, turn off [X-axis mirror] and shift the bones.

Turn on [X軸ミラー] again.

As is: Bones are not deformed.

Move bones: Align to first selected bone

From the above, when rigging bones, it seems better to turn on [X-axis mirror] and adjust the overall position, and then turn off [X-axis mirror] and make detailed adjustments.

Reference

Blender – cg.xyamu.net

Operating Environment

• Windows10 Pro
• Blender 2.81, 2.90
• 3D model (Eraiser) It is easier to do if it is symmetrical
• Rig for VRC – Booth