What is the best program out there that can open STP files and export it as well?
CON: You can't measure anything to check the size of the part. The free eDrawings viewer from SolidWorks lets you measure, cross section, and much more but it does not open STP files. The eDrawings viewer opens several CAD file formats, 2D and 3D. Wish they would include STP.
There is a CON: it can only display a file but not export it into anything else.