Solidify landscape mesh for 3D printing

Hi all,

I want to create a landscape as a solid, thin object (1-2 mm thick) that I can 3D print.

So far I have created a landscape mesh using the displacement modifier and a greyscale image heightmap (which I made from some DEM files). As the landscape represents the whole topography of Norway, the surface is highly complex (150.000 faces or more, if possible).

However, I am not able to extrude or “thicken” this surface so that it has an even thickness. I cannot simply extrude the surface, because that would result in uneven thickness. I need an even offset from the first surface. When I use the solidify modifier, the resulting geometry is very poor, with lots of thin faces, intersecting faces etc (I use the 3D print toolbox to inspect the model).

Any suggestion? Is Blender up for this task at all?