RubberHose 2 - RubberRig
Create layers in After Effects or import from Illustrator and Photoshop. Align the connection point of the two layers at the center of the comp (keyboard shortcut: ' ). Select the first layer of the chain (typically the upper leg or arm), followed by the end layer of the chain (typically the lower leg or arm), then press the New RubberRig button.
The art layers will be connected to a new set of controllers that function like the stretchable RubberHose controls you know and love.
A defining feature of RubberHose is the stretching that happens when controllers are dragged beyond their Hose Length. Stretchiness has now made its way to layer rigging.
The initial length of each layer is defined by the Segment Length control in the Effect Panel. Dial this in to the correct length if it's not exactly right after creation.
Some limb segments are longer than others and this length difference can be adjusted with the Center Bias control on the Center controller's Effect Panel.
Depending on how your art was created or aligned this automatic setup might not be perfect. Use each layer's Rotation property to align it's end to the corresponding controller. Use the layer's Anchor Point property to align where it joins the other layer.
If your rig creation produces some kind of weird, inside-out rotation and alignment, it's probably because of the order in which you selected the layers. Be sure you select the top-most layer first (upper arm/leg) then the lower layer before creating the rig.
Select layers in the right order or embrace the weird looking.
remember: Duik is really powerful
RubberRig is not the perfect tool for every project. If you're trying to achieve something more complex like 3 layer IK or bezier IK setups you should absolutely check out Duik. It's has a robust feature set and is more accurate when working with externally created art layers.