EDIT: I am still uploading the Negative STLs. . . [DONE!]
Thought I’d offer up some random height maps that I created from the website @Julien linked to a while back. I modified the original random height map generator and created a bunch of STLs from the PNGs as I previously described here.
Here’s the STL made from RHM_001:
Here’s the STL made from the RHM_001_Neg: