I’m trying to create a cartoon type rig, and I wanted to know how to add the controls that create the S and C shapes on a character’s stretchy limbs. I already know how to rig a stretchy arm and leg, but I can’t seem to find a tutorial for creating these particular controls.
You can achieve that by using Spline IK. If you have a few knots along the spline, and cluster them (parenting the upper arm knots to the upper arm and the lower to the lower etc) you will get an IK arm that acts normally but with a set of sub controls which you can animate over the top to create more elaborate shapes.
My personal preference is to work with “flexiplanes” or “ribbons”. Digital Tutors goes over it in Advanced Character Rigging in Maya 2013, which will give you a simple way to go about making one and how to implement it into your rig. There’s also a video here that gives a demo of a more complex version. I’d follow along on the tutorial to try to understand how it works in case you need to mess with it, but there’s also a handy script that does it all automatically which he provides in the description.
You’ll also want to look at his video about creating a twist extractor for some clues as to how to keep them from flipping when you rig the arms.