I wasn’t aware of having to turn the “wire” button on. However, it doesn’t appear to help.
Uh oh… I set up a little test project, and now even x-mirror is not working for me when building an armature.
I presume I can just build an armature, without a mesh, with x mirror and it should mirror across the x axis. Hey, this worked for me before! Either I’m doing something subtly wrong, or something is amiss. I doubt there is anything amiss, however, since both version 2.42a and 2.43 do the same thing in test projects.
Sorry that this has somehow drifted to another point, but perhaps it’s the same problem I’m having.
Here is a screen shot of my test project. Note, In the screenshot I’ve extruded a bone along the x axis, and it’s not being mirrored.
Create half the mesh, use the mirror modifier to create the second half, then apply the mirror modifier, create half the armature (and the bones in the middle), then name each bone according to <name>_R (for the right side of the armature, as viewed on the screen).
Mirror the bones that need to be mirrored (ignore the bones in the centre), then select them in edit mode, press W and choose “flip names” that will automatically rename them.
After that you add the armature modifier to the mesh as normal, and press CTRL + A to apply rotation/location, then do the same for the armature go into pose mode, then immediately select the mesh and go into weight painting mode, then be sure to enable “X-Mirror” in the Paint panel, select a bone, start painting, and it should copy the weight paint over to the other side, and also create a vertex group.