I've now got a 'Good' model of the payload bay complete with cameras, Aft and Forward bulkhead hand rails and I've even got a half decent Orbiter Docking System modelled. I'm now working on the Shuttle Remote Manipulator System, which I've got minimum information to work with. Too much of it is 'best guess' with little, obsolete or incomplete drawings. The best source has been a document called "Space Shuttle Technical Conference, part 2". It's given me enough to create something that I can perfect at a later date. I think I've done all right with the lack of real data.