Programs enabling conversion of the file:
If your objective is to convert the file from 001 to the file 3DD, you can use any of the applications listed. 001 to 3DD conversion process in every program intended for this purpose (so-called converters) is very intuitive and everyone is able to manage converting a file.
However, bear in mind that the list may also include programs to support and work with the indicated extensions 001 and 3DD - and not only converters. In such a case, you need to open the source file 001 and from the options available in the program, choose ”Save as... 3DD" or "Export to 3DD".