A few weeks back, case-inc released their monthly app. The February 2012 instalment was a tool which allows you to convert a Room to a 3D Mass.
More details can be found on the case-inc website ….http://apps.case-inc.com/ The tool is really valuable, however, the initial release had some limitations. When you converted the Room, it was actually converting it to a Generic model. Not a big deal, but you needed to be aware of this. So after some positive critical feedback, our friends at case-inc made some tweaks! So now when you choose Rooms to 3D Mass, the output is indeed a 3D mass family! Now all they need to do is find a smart way for us to automatically name the generated families rather than a have a long winded database name; did I say I was demanding? ;-)
Well done guys & a big thanks you from the Revit community. :-)