I've started version 1 of a brush for zbrush made specifically for the hard surface dynamesh process.  Each primitive can add or subtract from the main shape and step up in resolution nicely to be polished.  I made the shape above in only a couple of minutes using this brush.

So far it's pretty basic shapes.  I'll be adding more to the brush and re-posting new versions.
Version 1.1

Try it out - Download HERE

More on this process can be found below: