|Flamethrower: Too small on first try|
First of all, it does make sense to stick to the standard scale for Unity projects (1 cube height = 1 meter). It really does.
Without having read the very useful manual about Unity Physics first, our 3D objects were modelled about 10 times larger than that - as a result, it would look like they are falling way too slow, with a gravity that would look believable on the moon (huge things look like they fall slowly, because they are so huge).
So after having the overall scale set, the next challenge is keeping it consistent. How big is an arm in relation to a body, how much bigger than a rocket launcher can the propeller be?
One technique that has proven quite useful is having a reference object in the 3D modeling program - e.g. a cube that is as big as the Unity cube and therefore 1 meter high, or also an already finished weapon when making another one. If the rocket launcher is in the right scale already, holding it next to the work-in-progress-flamethrower while modeling gives a good idea of proportions.
|Saw, first version|
|...and larger version|