In no particular order:
1. the Zeppelin works construction sheds at Friedrichshafen to complement Graf Zeppelin or Hindenburg models (I know that Ralph Currell created models of the sheds at Cardington to accompany his R100 and R101 models)
2. launch tower to accompany the Energia-Buran model at
Space flight paper modelling
3. Star Wars, Tantiv V - it seems like a model must exist, but I haven’t stumbled across it
4. Star Trek - large scale Cochrane warp ship from from First Contact (I do know that there is a smaller-scale kit in our Downloads area)
5. a 1:100 scale Hindenburg or Graf Zeppelin; I know there are accuracy issues with the Schreiber-Bogen kits (lettering color, among others); there is the Alin 1:200 kit that is believed to be free—some of Alin’s other extremely high precision kits are in the Downloads area.
6. a gigantic Hughes H-4 Hercules
7. a gigantic model of the Voyager spacecraft