dnbforces:
Depending on what you are trying to accomplish, a few more options:
1. For a walk-through 3D Model, try saving the AC file in the BIMx format. With BIMx Pro, layouts can be added to the file.
2. The other user can install AC 19 without a license. They can open and view the file in Demo Mode, but will not be able to save.
3. Save the file as DWG from the 3D Window, then the other user can open that file as an Object. It will be a single object of the entire model.
David