A great compliment to “Sketchup” is a handy little product from Japan, “Pepakura”. This tool creates a printable, origami-like pattern from which 3D models may be translated into paper “reality”.
Here at the University of Texas, I write 3D games that deliver educational content for middle-school children. I use Sketchup as the starting point in my workflow for all the 3D buildings and many of the other objects that the kids move through, as they navigate within their virtual world. For $38, this gadget allows me to push my models through a color printer — I fold the output and paste a few ends together with a gluestick, and I have something to hand to the kids as an incentive when they finish the program. They think it’s neat to hold something in their hands that they had just been interacting with in the virtual world.
Nearly anything that you can model can be printed and brought into this world, in all of it’s 3D glory.