How to make a Geography Model? Please help!?

I've been given a Geography Homework on Model Making. The topic is Major Landforms of Earth, that means, landmes like mountains, plateaus, plains etc. Today is Wednesday and the project has to submitted on Tuesday. I have decided to use thermo col on which to make the model. Well, the easiest part is to make plains, but please help me with it. Please tell me with what materials and how to make mountains, plateaus and plains. Please help me with the model!!