Summary: We present a method for rendering 3D models in the traditional line-drawing style used in artistic and scientific illustrations. The goal is to suggest the 3D shape of the objects using a small number of lines drawn with carefully chosen line qualities. The system combines several known techniques into a simple yet effective non-photorealistic line renderer. Feature edges related to the outline and inferior of a given 3D mesh are extracted, segmented, and smoothed, yielding chains of lines with varying path, length, thickness, gaps, and enclosures. The paper includes sample renderings obtained for a variety of models.