A complex planar mechanism is usually represented by its simplified schematic representation, called the kinematic skeleton, in both synthesis and analysis. Unfortunately, interference between links may not be evident from the kinematic skeleton. This paper presents a computer aided top-down technique to design the geometry of an interference free mechanism. The method is intended to replace intuitive and trial and error link geometry design techniques. The geometric design of the links of a mechanism is initiated after the kinematic skeleton diagram is created using existing synthesis and analysis techniques. The solution to the interference problem is initialized by placing links into different layers. To ensure a link, called a reference link, does not interfere with other links within its layer, the work space of those links with respect to the reference link is generated. The resulting domain, called a "swept area", establishes an illegal region whose complement identifies the feasible region to place the geometry of the reference link. The new method is demonstrated with an example.