Combine Bump 3d and Bump 3d together

connect multi-Bump 3d node and keep their it's own bump value control:

First show Left and Right hidden

Out Normal -> Normal Camera


This also work on 2d bump chan, too! And also chan 3d bump and 2d bump together...

This give you different level of bump control, and easy to see!
sample maya file!

Other bump resource on internet!