Document-Setting »�Snap to objects�«
Snapping to the edges of threedimensional objects in VectorWorks is a very convenient feature. To enable it, ensure the palette �Constraints� is visible. Then double click on the tool �Snap to object� and set this setting in the dialog �3D Snapping�:

This setting is a document setting. To enable it permanently, set it in your favourite template drawing and save it as template anew.
