I didn’t have time to do a lot today but I did manage to get a start on the textures. I made color and specular maps for the upper saucer (I’ll add weathering later.) The spec map doesn’t do much in this lighting but you get the idea.
I used the color picker in Gimp to attempt to get the correct colors for the Ambassador-class from a photo. However, that’s easier said than done due to lighting, but this should be close.