When I was trying to construckt an Orb base I came to the point I had to work with parts of the model. This for a construcktion scene.
So I reconstruckted the model with brushes, but when I was ready the model needed so many brushes I could only use a few in a small map.
http://members.home.nl/gimli/orbqu.JPG
Then I remembered the voidents from wazat, which includes mdl files, so now I'm using parts of the model in facts. They tend to use almost no data.