Export Workpieces
Assemblies and parts added to a station can be exported from the workspace widget. Any assembly/part can be exported by selecting the assembly in the workspace widget, then right-clicking and selecting one of two available export options in the context menu:
Export as STL…
Export STEP…
All children of the selected assembly will be included in the exported file.
If STL is selected, all sub-assemblies and their parts will be merged into a single model before being exported to the selected destination.
If STEP is selected, the exported STEP model will retain the structure of the model. All sub-assemblies and parts will be kept as individual components and maintain their position in the model tree.

Export options in the context menu
Selecting a user-frame then exporting will export all assemblies added to the user-frame, even if they were added separately.