Very good work. I know for sure I could never do something this good. However, I feel like I'm seeing random lines near the top/center of the biggest ship/tank. I know that those squares are meant to be 3d looking and create depth, but without looking at the zoomed in version, it's hard to tell. It would be great if you could make the contrast a bit better on those areas. I also feel on the large one the sides have a bit too much black than they need - maybe use some dark blues there. Other than that, tremendously great job.