Most of the time it is easiest to draw a model using a 2D cross-section on a 2D plane, then extruding the model into other directions in 3D mode. Starting with version 6.0 many planes are available for 2D drawing and surfaces drawn on them are automatically recognized in 3D.
Some of the commands that you may find useful during your 3D model construction are: MERGE and VISIBILITY. MERGE command enables you to: model a part of your geometry, save it, and later to merge with other parts to create your final model. The VISIBILITY command enables you to make part of your displayed geometry temporary invisible. This allows you to focus on the part of the model you want to concentrate on.
To reduce model design and analysis time significantly the symmetry and periodic features are of great benefit. The “Symmetric” and “Periodic” commands are helpful in reducing the geometry size if your model contains symmetry or periodicity.