Pen-based interactions have been ubiquitously adopted on mobile and stationary devices, but the usability can be further augmentedthrough the use of advanced techniques. In this work, we propose FacialPen, a prototype that uses facial gestures to trigger commandsfor pen-based manipulation. In our prototype, a fisheye camera is mounted to the end of a stylus that provides a broad view fromwhich to capture the human face. We facilitated an elicitation study to identify natural and user-defined gestures for interactionswith facial expressions. Different gestures can be further discerned via face detection and a classification pipeline. We designed asketching demonstration application to explore usage scenarios and evaluated the effectiveness of FacialPen through a qualitativestudy. The user study posits that FacialPen supports efficiency by reducing screen widgets, enabling the continuity of creation workand liberating the user’s stylus holding postures when switching sketch functions.