Unless you’re gonna have a controlled light source and restrict the viewing angle to one, like in a shadow-box, I’d pretty much advise against it… It might be a doable effect if photographing the diorama is the primary goal, but not for general viewing with the Mk I Eyeball…But otherwise, IMHO, it’ll look exactly like what it is… Paint…
If you do a shadow-box, you can put in a direct light-source to simulate harsh sunlight and then the shadows cast naturally would be enough anyway… It’s easy to fool a camera, but the eyes are another thing…
If you want to use painted techniques to pull off an effect you really need to know what you are doing and have a specific point to make.
Whilst not exactly on topic, I think this one really does a great job of showing what’s important to the kid by having it in colour whereas the rest of it is in black and white.
You’d have to go further than just the shadows to carry this off. You’d need to paint everything with a very directed light source in mind. In the case of a carrier deck, assumong there’s an aircraft, you’d have to paint the side of the a/c facing the sun brighter than the side away from the sun while still conveying the “correct” colors of hte a/c. If you are talking a setting sun, you’d alos have to adjust the color values to a red shift as the light goes through more atmosphere causing a warm glow to the light. The interior of the cockpit would need to be carefully painted to match the angel of the light source. The lower the angle of the light source, the more challenging your task. You’d need to use reverse perspective, with relatively small shadowing near the gear, for example, getting wider and less intense as the shadow extends outward. This would have to be completely consistent with everything in the scene.
It’s one thing to use a bit of pastel to create the effect of a shadow for a figure when you’ve used zenithal lighting, but what you’re describing is one major undertaking.