Eskimos in space! Let's say, just for contextual concerns, that a band of water-rich comet miners want to use water-ice found in the outer Solar System as the main structural and functional component of their spacecraft. That is, the spacecraft and perhaps some of its basic support functions (internal atmosphere, electricity & propulsion?) are derived from the properties of ice.
I'm not concerned with the constructional methods of such a spacecraft (given my source outlines it quite humorously), rather, How might a spacecraft of water (and any material state thereof) perform the basic aforementioned functions of a classical spacecraft?
The icestronauts have access to items like fission/fusion technology, and all the wondrous advancements of the current day, and any number of these things may be incorporated into the spacecraft's design, so long as the bulk of it is water-ice.
If you don't want to read the source—which happens to be practically the only source I can find for such an idea—the idea behind the ice spaceship's construction is this: launch a plastic "mold" into space (quite like an inflatable tube one might see at the beach), and fill it with water. Freeze the water, spin the thing up, and you're done! A functioning von Braun wheel made of ice. Now, my idea here is to attempt to expand upon this, make it feasible and practical: Water may be used as fuel; It can be heated into a gas and expelled out at high velocities; Oxygen can be ripped from H2O molecules; it has certain radiation-shielding properties; etc.
Postscript: the icestronauts are willing to settle on the use of other ices as well. Consider it an extension of the previous limitation of the addition of other technology to support the bulk of water-ice.
Edit: assume no other external factors will destroy the spacecraft; our icestronauts are not that foolish. Consider their efforts as R&D, searching for viable methods for this endeavor.