Runners define a path of trajectory for a feature. You can define a flow path for a feature by either sketching it on a plane, or selecting any datum curve as the flow path. This curve can be a simple 2-D sketch or a complex 3-D curve.

A runner's cross-section must be constant. To maintain a constant cross-section along any specified geometry, position the section of the runner so its origin is located normal or perpendicular to the flow path it is placed on. For simple 2-D planar runners, always position the section parallel to the pull direction. For complex 3-D runners, always position the section normal to the curve that defines its flow path.