We present DesignAR, an augmented design workstation for creating 3D models. Our approach seamlessly integrates an interactive surface displaying 2D views with head-mounted, stereoscopic Augmented Reality (AR). This creates a combined output space that expands the screen estate and enables placing 3D objects beyond display borders. For the effective combination of 2D and 3D views, we define different levels of proximity and alignment. Regarding input, multi-touch and pen mitigate issues of precision and ergonomics commonly found in mid-air VR/AR interaction. For creating and refining 3D models, we propose a set of pen and touch techniques with immediate AR feedback, including sketching of rotational solids or tracing physical objects on the surface. To further support a designer's modeling process, we additionally propose orthographic model views and UI offloading in AR as well as freely placeable model instances with real-world reference. Based on our DesignAR prototype, we report on challenges and insights regarding this novel type of display augmentation. The combination of high-resolution, high-precision interactive surfaces with carefully aligned AR views opens up exciting possibilities for future work and design environments, a vision we call Augmented Displays.