Your model is more than just straight lines. SketchUp can help you create curved geometry using arcs. Before you begin drawing arcs, here are a few handy details about the way arc entities work:

With the Push/Pull tool (), you can create a 3D shape from a face or cut a 3D shape out of your model. You can push/pull any type of face, including circular, rectangular, and abstract faces.

SketchUp offers two tools to help you select what entities you want to modify with SketchUp's other tools and commands - the Select tool (), and the Lasso tool (). Here's where you find these tools in SketchUp:

Many models start with basic shapes. In SketchUp, the shape tools help you draw rectangles, circles, and polygons. You find these tools on the Getting Started toolbar, the Drawing toolbar, and the Large Tool Set toolbar.