Another 3d-printer here, great. I have two Reprap-based printers here and they work great for me.

For your problem, you may want to give blender a try. Take a box, use a suitable subdivision modifier without smoothing with an displacement modifier on top of it. You will neeed a box which is mapped in a way that the image you load will be applied to one side only, (the top, probably), and depending on the desired resolution, you may need to apply the subdivision surface modifier twice or even more often. Don't forget to turn off the smoothing! (not "Catmull Clark" but "Simple")

When printing stuff like this you should use a fine layer height, like 0.1 mm on the Z-Axis. 

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

Avatar image of me done by Chidori.