Should be as tree-like as we can manage without being artificial... And yes, lights, or if someone can make it, fiber optic strings. Then you'll have coloured... or even multicoloured strings of light hanging from them.
[She wouldn't think like this usually, but it might be something Kay would like to see, so she's simply trying to think around types of decoration she remembers used from before the war.]
[Video]
[She wouldn't think like this usually, but it might be something Kay would like to see, so she's simply trying to think around types of decoration she remembers used from before the war.]