This construction toy 3D puzzle is made for laser cutting from the poliurethane foam sheet. It has enourmous number of parts, and features 3 moving railway carriages, one lift and a lot of other details. If uploaded as full assembly it is way to big, so I have done couple of complex parts so you can still move carriages and lift in the assembly. For the same reason I have excluded all aliens shown on the picture, but you can find them Aliens and robots for Alien city 3D puzzle toy

UPD: For some people wanted to make this toy, the DWG files were added (under AutoCAD) These files include complete set of pieces prepared for laser cutting (Just feed the DWG into CNC cutter and enjoy assemblying it), In terms of the material you should use polyurethane foam (yoga mat sort of thing), the reason is the interlocks are designed in terms of this flexible thing, so you cannot cut it from plastic as it will be impossible to assemble. The files are named for different sheet thickness you have to use: 3mm, 4mm, 5mm, and 8mm (major components) respectively.
Please NOTE the effort I put into disigning this thing and do not use it for commercial propose. But other then that you are welcome to produce or do whatever you want with it.