Well u cant stroe 3d models directly into a file , i suggest the following approach,
1] Have a ThreeDModel Class that has all the data associated a particualr 3D model.
2] Now u can create a 3DModel object from such a class by creating a object and setting the necessary parameters for that object.
3] Now Have a XML file called as ThreeDInfo.xml , which will have the following structure.
<Attr 1> </Attr 1>
<Attr n> </Attr n>
The attributes are the properties of a 3D model.
Now when u want to render a model u can directly read the XML file to get the particular model.
If this doesnot work for u , do reply back :)