Fittings and all equipment were modeled in Vectorworks.
3D PDFs can be created directly from a VW2011 DWG export but it takes a lot of rework in Acrobat to get it right. AutoCad can also produce 3D PDFs but it a bit harder to get the transparency working correctly (you have to assign it via materials, etc.).
MicroStation V8I just does a really slick job of conversion. You can open the DWG file (exported from VW), save it as a DGN (Microstion file), revise the layer data (classes) as needed and print out the 3D PDF model.
VW2011 does have some real problems when exporting DWG files with complex extruded polylines that they really need to fix (way too much time revising in AutoCad or Microstation).
Cheers, Win B.