Colour theory help

[coldstare6]

I'm doing some 3d modelling, and I've decided to give the turret I'm doing a space-ish colour scheme for it, which I'm achieving with a blue-grey colour scheme, but that's literally all I have as a colour palette: One shade of blue, one shade of grey and one shade of black. I know that this colour palette may be limited, but I dunno, it just feels a little empty. Any idea what other colours I could employ?

Here's what I've got so far, sorry for wierd lighting, Maya's wierd like that