Create extruded 3D solids in FME

Hi,
I'm trying to create extruded 3D AutoCAD solids from a table of data
containing coordinates and level information. Using the
3DPointReplacer, Bufferer and Extruder, I am able to create 3D mesh
objects, but not true solid objects. Is there a format attribute of
DXF/DWG that I can set to force solid creation, or is this just not
possible in FME 2010?
Thanks,
Richard