Files with d2d file extension can be found as CAD files from 3D Fassade Plus program. Seems like old.
D2D file extension - 3D Fassade Plus CAD data
What is d2d file? How to open d2d files?
File type specification:
The d2d file extension seems to be related to old CAD program called 3D Fassade Plus and used for its default CAD file type.
Seems like old and no longer used product by now.
This d2d file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.