A Part file is a file that is created in a 3D modeling software package. Some examples of Part files are files that have an .stl, .zpr, .wrl, .ply, or .3ds extension. Build files (which are also called Part or Document files) have a .zbd extension and is unique to the legacy ZPrint software and to 3DPrint. Build Files include the set of Part files oriented in the Build Bed.
You can open a single Build file, or multiple Part files, into the 3DPrint main window. When you save changes, or exit 3DPrint, 3DPrint prompts you to save the Part file(s) as a .zbd file (a Build file). Save a Part file as a Build file to keep all of the modifications that you have made to the part(s), along with the printer/powder settings you have selected for that build.
You cannot open a combination of Build files and Part files into the 3DPrint main window. Only one Build file at a time can be loaded into the main window. If you try to open more than one .zbd file into the same window, 3DPrint will ask you to select a single document (Build) file, or several Part files.