Sophia Zauner provides a little quick tip for Autodesk Maya where she shows how to use OutMesh and InMesh connections in Maya and postulates on its uses in a rigging pipeline.

using a Shapes .outMesh Plug and driving an others Shape .inMesh is a really powerfull trick. It gives you the possibility to let Shape A inherit its form from an Shape B, but still beeing able to make changes on ShapeA (unlike, if you would use for example an instance.)

A single object in Maya is generally comprised of a series of nodes which is incredibly helpful in production and even animation. A simple polygon cube will be built from a transform node, a polyCube node, a shape node, and shading group node.

So, as a tangent, but on a similar premise, in rigging you have the option to make controls out of anything typically that does not render, and the most popular technique is to use simple curves, this has its advantages as Maya has selection priority and it may be more convenient to have controls that are curves for the purpose of selection during animation.

Simply messing around with the standard object connections, it is possible to use polygon shapes for controllers in some cases, by simply disconnecting the shape node from the shading group node which will leave you a shape that does not render.

Expanding on this premise, Sophia shows that you can directly pipe the Mesh attribute from one shape to the other so that the shapes in the viewport will share an inherited mesh, and the video shows a polygon cube taking on the attributes of a polygon sphere.

This has all kinds of possibilities in a lot of different workflows, and Sophia notes one of them to be BlendShapes in a Character Rigging Workflow.

This will open up the possibility for iterations over many BlendShapes that are already connected to the character where you are able to create changes on one of them, and have those changes propagate towards the other BlendShapes for the character. By simply rerouting the outMesh and inMesh connections from shape to shape, you are able to create a simple solution to a task that would have taken quite a bit of time to execute correctly any other way.