VR Sketchpad why 
related work 3D eCAADe 
system demo discussion thanks
Related Work - 3D Sketch Systems
- SKETCH (Zeleznik, Herndon et al. 1996)
- 3D Solid from 2D Drawing (Grimstead & Martin 1995)
- Digital Clay (Schweikardt & Gross 1998)
- Quick-Sketch (Eggli, Bruderlin et al 1995)
- DDDoolz (Achten, de Vries et al. 2000)
- Teddy (Igarashi, Matsuoka et al. 1999)