CamSketchpad is a recreation of Ivan Sutherland´s seminal Sketchpad program. CamSketchpad is a CAD / 2D drawing program with support for geometrical constraints and the inclusion of instances referencing other drawings.
CamSketchpad is far from being as complete and efficient as the original Sketchpad, but it does have all the necessary components in a rudimentary form, and is finished enough to be usable.
Requires Java Runtime Environment. Get It Here.