Animating machine

Hi,

I am making small “game”, where player can operate machine. It is supposed to work in first person view where player points at differend bits and knobs of the machine and clicks them, and the machine model does its thing. Now i am thinking how should i go about modelling the machine.

Should it be one big 3d model with rigged parts, or seperate objects for each moving part? (the machine does not have any parts that deform (bend) as it is doing its stuff)

Advice and suggestions appreciated.

Separate pieces would be best.
Since there are no bending pieces, and if rigging might be an issue, you can always animate in Unity. for the individual components.