I've not really got my head around the possibilities of 3D printing but when I see small models like this I realise that anything's possible!
This rocket truck complete with Nike Hercules can be found on Shapeways the 3D printing marketplace.
Try searching for Blackbird SR71, Dyna Soar and Saturn V engine!
The prices are allover the place but some stuff's cheap.
Has anyone 3D printed a space toy part?