Attaching Global Unique Identifiers (GUID) to objects

Hi

I am adding instance data to my 3d modelled objects in AECOsim Building Designer (Structural). The objects are modelled by me and are not AECOsim objects from its library.

I have a few objects in my model that are not in the instance data catalogue so I cannot pick anthing from the catalogue.

All I want to do is attach to the objects a GUID and don't really need any extra properties coming through. Just the GUID number.

Does anyone know how to do this?

Thanks

Mark