I do not have pro/e software. I hired a company to build a pototype for me. They used pro/e. I have the prt files on disk. I need them in stl. They went out of business. I hired another company to complete the work. They can not open all the files, for some reason, to convert the prt files to stl. I have not been able to find any trial software online to complete the conversion. Is there anyone out there that can suggest anything? such as downloadable free software or anyone that can convert the (7) files for me.