Rob,
I tend to do the same thing with brass. It is easy to work with, and when used in a way that shows, it looks good too.
About the battery change up, if I were to use D cells in this manner, along with the 9v batteries, that would be the time to consider a separate power chassis. Having said that, it would lend itself to even more chassis configurations for the Quickie. Even though simple, I don't like having to take the batteries/cells out from among the circuit. A separate chassis would solve that problem. Off to the drawing board...