Exporting generated lattice and surrounding structures

The Cubit documentation clearly demonstrates how to output the newly created lattice structures to a VTK file which can be opened in paraview. I was curious how (or if) other volumes could be exported without applying a lattice to them as well in the same file. I have found that I can output the other structures with the ‘Export uspline’ command but upon asking for a VTK output, cubit gives me a VTU file. It still reads into paraview fine, but I would like to then output the data to an STL file which seems to be troublesome for the VTU data. Any insight would be appreciated. Thank you!