This paper presents the development of a tool which is capable of compute several projections of a polyhedral scene from a single axonometric or perspective projection. This projection is hand-drawn and may be incomplete. This sketch can be rotated with a kind of trackball and the tool computes in real-time new projections. In that way the designer can choose another view from which he is able to control and complete the sketch and carry on designing. So this tool can be useful for exploring architectural forms in the early phases of the design process. Unlike others freehand sketching interfaces, the system does not operate any reconstruction in 3D. Everything is computed in a 2D world.