Save assembly as part file. What can i do with it?

In the multipart body you have you can use move body feature to move "parts" with.

I would recommend that before you do this type of save that you make a copy of the folder/assembly - so if you need to make changes etc you can always pull up the original, make your changes and re-save...

After you save as part, it's kind of a dumb file.  There is no connection to the original.

We use them to save out models for customers.