STL to Stp

 From:  ACP
10892.1 
I need to import stl files from Printables for modification using MOI 3d. I do the conversion using FreeCad. The stp file exported from FreeCad and then imported into MOI 3d are MOI surfaces (and edges??) only.. These are then hard to incorporate into solid items because they look like a mesh with triangles (edges) that are far too dense to work with.
Any other MOI to Prusa printers out there??

ACP