Create a weldment and cut list. Add a custom property to a body. RMB on the cutlist icon and select save bodies. The property manager gives an option to save the custom properties. The ones that were added to the bodies don't get copied through to the part that is created. Why not? Is this intended behaviour? See files below.

Autocad Inventor apparently saves the bodies created as you develop a welment as a part automatically. I see some merit in this. I think the appproach by SW could be better if it was working well. It gives the possibility to save the bodies of a part out after it was created as a weldment in a single part file. At present the hassle is that you need to open each part file of each body saved out to add the required custom properties. 2010 adds a nice feature in which the custom properties of bodies can be viewed simultaneously and changed easily. That loses its benefit if the properties associated with the body don't get saved out to the part files.

Most of the people I have spoken to modelling and detailing significant steelwork structures using SW  work on the rule that if steelwork is welded, it stays in a single part file. If it is bolted together ie. beams, columns, bracing and brackets then the individual members get created as part files and inserted into an assembly. You would then use a drawing BOM rather than a weldment cutlist to list member custom properties. It would be helpful to be able to do the initial structure as a single weldment and then save bodies out to an assembly containing the saved parts. Where required parts could get dragged into subassembly folders. Anyone doing this at present?