I’m rigging my Gundam fingers with Blender.
I am trying to restrict rotation on the x-axis so that it cannot be rotated. (The part marked with x in the attached figure)
Where and how should I set the suggestion so that it does not rotate on the x-axis?
Select a bone while in pose mode. Look on properties/bone/transform. There’s a lock icon next to all your transform channels. Click that icon to lock that channel, which prevents changing of it (via some means, not via others.)