In this tutorial you'll learn how to use the default edge render option in Blender in a more flexible way using the Compositor. Topics handled are: how to control the amount of edges shown and how increase or decrease the size of the edge.
In the latest Blender official version: 2.67, Freestyle NPR Rendering made it into Blender official builds (it was only available in test and experimental builds for a long time before). It works with Blender Internal Render and it allows us to create lines in the place of edges, contours, silouethes, etc.
This helps a lot creating 2D artistic renderings imitating drawings, cartoon effects, cell-shading... even create an image that looks like a blueprint from a 3D model. This last one is what we're gonna do in this tutorial :)
Original post at blendtuts: http://www.blendtuts.com/freestyle