First of all, I am going to talk through the setting up of the IK and FK switches; this was a fairly easy thing to set up in both arms. In the last post, you may have noticed, in the screenshots, these NURBS circles that were located at the shoulders and elbows; in addition to the wrist curve which I did mention in the last post. These were going to serve as my FK controls and I needed to set up a system
Next, I needed to Constrain the wrist curve to the elbow curve. However, I could not do this the conventional way as the wrist was already parented to the IK Handle control and this would mess up the hierarchy.
I resolved this by creating a group for the wrist curve only. As the wrist curve itself was parented to the IK handle curve, I parented the group, to the elbow curve. Now, when I rotated the elbow, or indeed the shoulder, the wrist would follow because the wrist itself was still constrained to the IK arm control but the node that I had put the wrist into would be parented to the elbow. This is a neat trick that I will keep hold of for whenever I am at risk of disrupting any constraint or group hierarchy.
Now, here is a video to remind you of what the character rig is capable of doing so far.