Thanks for the tips The glow was a texture map applied to the glow channel The references for cloud city are sparse I used SW essential guide to vehicles & vessels, for dimensions it has a "blueprint" for cloud city by Doug Chiang. Texturing was harder I used the Star Wars chronicles and The SW Archives. Unfortunatley in empire cloud city was a matte painting and in the 1997 release it was digitally replaced so there are not many if any photos of an actual model