Personal Work.
This started from me just playing around with some shapes in Maya until something looked good. I had no real direction other that I wanted to come up with some kind of unusual spacecraft. Coming up with an original shape was more important that it being functional. Half way through this process I decided it was looking too much like a regular spacecraft, so I turned the model around and made the back the front :)
Last thing I decided on was it's function, purely based on what I thought it looked like it might do. The four circular protrusions looked like they could be used to push something, like a tug boat would. Deciding on making them magnets just made sense of the shapes and added the final plausible functionality.