Perhaps to make maximum use of that space a handegg shape would be best.
Corrected that for you. A "football shape" is a sphere.
In America, a football would mean an American Football football. That is not round.
In Australia, a football could mean the ball used in any of: Australian Football, Rugby Union Football, Rugby League Football, or Association Football.
In Ireland, I believe, a football generally means a Gaelic Football. Unless the person using the word means a rugby or association football.
I admit I don't know what I would get if in England if I asked for a football without specifying which of the three versions played professionally there or any of them versions played by amateurs only.
This is a thread about a warp drive, not a thread to parse the incredibly array of meanings that the word football provides.