This is the whole rig so far against the reference image:
Lower limit:
Upper limit:
Improvements to rig:
For the hinges I realised a bit late that rotation copy modifier was overkill…
They don’t rotate locally so this constraint is fine for this rig:
It just locks that bone in place relative to the parent. Can’t get rid of these bones because the hinge meshes rely on them.
UArm1 was rigged similar to LArm1.
Just realised now that the middle hinge looks a bit like a Suzanne silhouette… Hmm. 