More so than the other series, TNG frequently featured model starships used as decoration on the various sets. For set decorators models would be fairly easy to come by since most were commercially available. One thing that I've always found odd though is that on more than one occasion the models were GROSSLY in accurate. I'm not talking about little details being off...I'm talking about Constitution Class ships with nacells on backwards or missing entire pieces. The question is why? AMT kits were cheap and relatively easy to build. Not only were they easy, but they were usually hard to screw up (i.e. pieces would not fit together if they were backwards. Yet there were models on TNG sets that were all kinds of screwed up. The question is why? I seem to recall a constitution refit model with the nacells lying on their side. That would have been intentional given that the model, out of the box could not do that.