You need a sketch?!
Okay here's something I did in half an hour.

It's nothing but a box really, nothing high poly. But with textures to make it look like its hollow. Something like what the Explorer has between the habitable areas. The black/red smudge in the middle is supposed to a walkway(tube) of some sort that could show up in the texture. So if it's used as a docking connection there is something besides ladders people can use to move back and forth. You're the model wiz so I am unfamiliar with your magic
It might be useful to give it a few docking points. In the ends and in the middle, so that worker bees and maintenance furys can move it around and surround the Thirdspace gate with these.
You could add some pipes in the surface, and add lights or glowmaps on it. And just a thought but a popcorn explosion (small or no expl.ani with lots of popcorn) without debris would look good with this (I don't know how it's done, but I've seen those before). If it holds fuel and oxygen it would just blow in to tiny glowing bits that would fade off.
That should give you an idea what I was thinking about. But if someone has something to add, then please do.