Scratch building help

I'm trying to build a UNSC cargo ship.	It's not really scratch
because I have appropriated parts from one of my UNSC DNs.

An animated raytrace is at:

http://jumpspace.net/raytrace/DawnTrader.gif

It's uploading at 128K (asymetric DSL) so it is a bit
slow, I apologize.

The engines come from the DN.  The spheres will probably be ping 
pong balls.  The girder structure in the center is the problem.
I may try to sculpt something and then resin cast it, but there
may be a better way, does anyone have any suggestions.

TIA

Roger