In fact they all came in light colors, grey or even white BUT they are all made from various parts, old parts, so it's not even, a panel should be light grey, another cream, another one like it was never used... Same for the markings.
It all depends on what squadron you wanna show. Every body know the Red one because of the Battle of Tantive IV, and the Death Star defeated.

But you can consider that there could be other colors, green, blue, yellow, orange, purple and so on.
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