SolidWorks

Once the part or assembly is created in 3D and is in positive space:
  1. File > Save As
  2. Set Save As Type to STL
  3. Options > Fine > OK
  4. Save

For a custom high-res STL file see below.

  1. File > Save As
  2. STL > Options
  3. Change the resolution to Custom
  4. Change the deviation to 0.0005in (0.004 mm)
  5. Change the angle to 4.75

For additional questions refer to your manual, MIS department or the Maker of the software: SolidWorks

Select your CAD program in the pulldown menu to view the recommended settings for exporting an STL file