Dear Sirs. I converted a .stl file into .geo (https://download.yousendit.com/Z01NSU5OOW5samQzZUE9PQ) for gmsh. I'm able to generate the surface mesh but it is not able to recognize the volume. Is it a problem in the file or it depends on the complexity of the geometry? Thanks in advance for the reply. best regards, Stefano Zinna