I recently discovered the best way to convert from a Rhino .3DM to TrueSpace: DXF. It preserves the layers from Rhino and translates them as sub-objects (I
think that's what they are...) in TS. Just use Rhino to save the file as a DXF - I don't know if 3D Exploration preserves the layers or not.
If anyone has any Rhino questions, just ask me. I can't guarantee an answer, but I'll sure try.

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"He who laughs last thinks slowest."
"Just becase you're paranoid doesn't mean they're not out to get you."
"To err is human; to really screw up you need a computer."
Creator of the
Sandvich Bar, the CapShip Turret Upgrade, the Complete FS2 Ship List and the System Backgrounds List (all available from the site)