This Spanish Galleon took me about one and a half years to figure out the processes necessary for making a 3D bass relief of this type. Notice the edges in the close-up images are not stair stepped like you see in most 3D bas-reliefs with hard edges. To the best of my knowledge, there are no 3D bas-reliefs as of yet of this type that have this high fidelity edge style.
This 3D bas-relief looks good as a low or high relief.
The format of this file is in STL. The download includes two versions, an open back version for CNC applications and a watertight closed back for 3D printing.