Well I haven't seen any ducts on the forms, but you can go out and adventure into "how to make your own"
programs you will need:
Segment editor
and FPSC
just run the segment editor, find the Scifi duct .x files and add them to the segment editor mesh bank folder then just build it, texture it and there you go, your brand new Duct Segment.
If you don't know how to use segment editor, then look up the Hints tips, I think theres help in there.
Im on dialup right now, unfortinatlly, so I can't go out and look for that tortorial for you I know theres one out there.
Good luck
pain
Me = noob
and i love The TGC : )