Need: An arm to move in a natural rotation at the shoulder. I have a photo of him playing the guitar that I want to move as though he is actually strumming the guitar.
Final mechanism used: rotating hub with pull-strip.
1st attempt: rotating hub with manual pull-strip.
Why it works: It rotates an image (or in my case, part of an image) around an axis point and allows the rest of the image to stay stationary. I like this mechanism because there is magic in the fact that your manual action (pulling the tab out straight) results in a different type of movement (a circle rotation).