Animator Joe Daniels posted an introduction to creating corrective blend shapes with the SHAPES Blend Shape Editor for Maya. Shapes give you a complete toolset for creating corrective shapes in Maya. You can create new shapes in a posed state, even if the other blend shape targets are active.
SHAPES Blend Shape Editor for Maya was created to reduce the amount of technical detail needed for the setup of corrective shapes, focusing on the creative process.
You can easily create the driving relationship for the generated shapes. This is done through either a regular set driven key based setup or the weight driver, a vector based reader node which is provided with SHAPES.
