If I loaded a STL file in MeshLab and I created a new mesh beside the loaded one, how can I export all of them as STL file ? Right now, if I export as STL what I see in viewer, I export just one mesh, not two which I see in viewer. What I missing ?
You can combine several meshes as previous step to exporting. Right click one of the meshes in the Layer dialog and select Flatten visible layers
. If you are working with point clouds, you must check the Keep unreferenced vertices
option.