You can build a paper card model version of the single-stage to orbit (SSTO) Reaction Engines Skylon spaceship : Papercraft Skylon spaceplane – Ninjatoes’ papercraft weblog
Download the pattern plan from the Japanese site I like paper craft (Google translated). The pdo file needs the Pepakura Viewer Download (Google translated).
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Find links to many more space paper models in the HobbySpace Modeling section.