Custom "3D Flying Objects" screensaver?
 

One of the included screensavers in Windows XP (and others probably) is 3D flying objects. It lets you choose from several models/animations that bounce around the screen. I'm curious to know if there is any way to input my own custom 3D object to appear in the screen saver.

Does anybody know if the included 3D models are stored somewhere in a general 3D file format? Do you think i'd be able to simply replace the 3D file with my own? Or are they hard coded somewhere deep inside a larger file?

If anybody has any information concerning this, i'd appreciate it :)
Thanks