To select bones while in Weight Paint mode in Blender 2.8:
- Select the Armature
- Shift select the skinned mesh
- Switch mode to Weight Paint
- Shift-Click bones to select them
* Shift double click to select bones hidden under the mesh
To copy bone constraints from one bone to other bones:
- In Blender Preferences > Add-ons:
Find the Interface: Copy Attributes Menu add-on, and enable it.
- In Armature Pose Mode,
Select one or more bones, and select last the bone that has the constraints you want to copy.
- Press Ctrl + C to open the Copy Attributes menu, and select Copy Bone Constraints.
Quickly setup bone constraints
To mirror a skeleton (Armature) in Blender:
- Create bones for one side of the rig and name them with “.L” for Left or “.R” for right.
- Select all the bones on that side.
- In Armature Edit Mode choose:
Armature > Symmetrize
Blender will create mirrored copies of all the bones with respect to the Armature origin and flip their names to names ending with the opposite side.
- When editing properly symmetrized bones,
The X-Axis Mirror tool option will simultaneously update both sides of the Armature to maintain symmetry.