LeoCAD is computer-aided design software for creating virtual LEGO models. This program has building blocks that allow students to create a virtual model. It's designed to allow new users to start creating new models without having to spend too much time learning the application. At the same time it has a rich feature set, enabling experienced users to build models using more advanced techniques.A bit tricky to start with, but worth the effort. Currently, about 10,000 different parts are available.