This may be inappropriate to ask,
But will there be a way to build custom Ships?
either in game or through moding?

As i read through the game page,
it just kept comming to mind
the ancient ship in Stargate Universe
and how cool would it be to try a run in that one.

And You...
Is there any particuçar Ship
you would like to build?
or see build for a run?

Thanks for the help.
Will try to find some stream or vid of this option,
to see how it works.

Can already see a dr.Nicholas Rush
isolated on the command chair,
and all other minions running arround.

And maybe Chloe, but only after the
alien intelligence mutation

is this a reference to a movie or tv show? I'm sorry I don't understand the reference.
to answer your question, space haven's sandbox mode doesn't do anything that I'm aware of except add an extra tab/area to the building menu and seems to leave the rest of the game the same. I had a great time with it and I had no trouble with it so far. When I'm not using it, it hides again inside the building menu no problem.