Abstract: In this work, a system for 3D sketching is presented. Instead of trying to process 3D data as geometric models constructed of surfaces or solids, the data is stored as 3D lines, preserving their form exactly as entered by the user. The 3D input of the system works by projecting 2D input from a single viewpoint to a grid surface that can be manipulated in real time. This enables creation of sketches with complex non-planar 3D strokes while still retaining the essence of pen and paper based sketching.