From exocad documentation
The last step in the wizard is the "Merging", which will:
- Combine (merge) all the individual elements you designed (copings, connectors, etc) into one or more meshes suitable for milling or laser melting. For each physical element you plan to produce, one mesh will be created.
- Save those meshes in STL format, with a _cad.stl file extension
- Write additional information (preparation margin, insertion axes, and much more) into the .constructionInfo file, which will be read by supported CAM applications
The saved files (.STL+.constructionInfo) will be located inside the respective project directory (the same one that opens when you use the 'Open in explorer' button in the DentalDB).
Merging and saving will start as soon as the dialog opens. The progress indicator shows the progress. You can stop the merging process with Cancel Merging , or restart it with Restart Merging . Once the merging and saving has finished, the resulting output files will be displayed in the box . You can use drag & drop operations here: e.g. you can drag and drop files directly from the box  into a directory of your choice, onto your CAM software, in an email composition window, or on an FTP server.
Once the merging is completed, the wizard is complete, and you cannot go back to any step. However, it's easy to reverse the process by clicking Remove Existing Merged Parts . This will allow you to
- Change the "Optimize" Setting
- Re-enter wizard/expert mode to change or adjust any available wizard or expert mode setting (see "Expert Mode" for more explanation).
There is only one option in merging Optimize for better free-forming or selective laser melting  (see explanation below). To switch to SLM optimization once you already have saved output files for milling, click Remove Existing Merged Parts , then Restart Merging .
Understanding the difference between output for milling and selective laser melting (SLM)
If your constructions are to be produced using selective laser melting (SLM, often incorrectly referred to as "laser sintering"), the output data must be a "watertight" mesh with certain specific characteristics:
- No holes or open edges; completely interconnected mesh
- No inner surfaces or self-intersections
The figure above shows a sectional view of the junction between connector and pontic, with SLM optimization (left) and without SLM optimization (right).
For milling, it is not mandatory that these special requirements are met. The post-processing for SLM involves time-consuming calculations, which is why the SLM optimizations (controlled by checkbox ) are only performed by default if a laser-melted material is selected in the DentalDB.
- If checkbox  is unchecked, resulting bridges cannot be produced using selective laser melting
- If checkbox  is checked, the resulting output is still suitable for milling
Click 'Finish' to close the wizard. You're done now, you may close the CAD window and proceed to the next job. Alternatively, you can still perform additional modifications on the construction by closing the wizard and using the context menu. See section "Changing a finished reconstruction" for details.
- I'm done  means that the design is complete. Simply close the DentalCAD window.
- Proceed to Production  Launch exocam CAM software (only visible if exocam license is present).
- Freeform Restorations  Opens a free-forming tool which can be used on the .stl. output. Confirm to save.
- Expert Mode  Shortcut to enter expert mode to make adjustments on the completed design (deletes the merged parts? requires re-merging??).
- Design Model  If the Model Creator Module is installed, this will start the tool, and remember all the margins.
- Save Scene in Project Directory  Recommended if there is a chance that the design may be re-visited later.