MESHLab is a very useful utility for converting and editing 3D meshes.  It accepts input in the form of .3DS, .OBJ, .STL and outputs  .3DS, .OBJ, .STL, and .DXF.  MESHLab reports errors if conversions exceed the permitted geometry stipulations of chosen formats.

 MESHLab is much more than a file convertor.  It is able to resolve the problem of "flipped face normals", a common fault when mesh files have been constructed making use of rotate and mirror functions. There are many other uses for MESHLab which go beyond the scope of this description. Click on the image to access the download, documentation and tutorial resources.