For this month's project on the Math Forum, I'm demonstrating how to set up a sectioned animation like this:
It's a great student exercise in 3D thought - figuring out what an object is based on section planes moving through it in a couple of different directions.
To see how this model can be set up, please see my FREE projects page on the Math Forum: http://mathforum.org/sketchup/projects_of_the_month.html, and download the April 2011 project.
Anyone can design anything in 3D! http://www.3dvinci.net/