In the past 3D CAD systems were slow, difficult to master and offered design engineers little flexibility for managing parametric relationships in their designs. Systems now on the market, however, require little training, in most cases a timeline of one to three days, and provide features that enable engineers to design their products more quickly, test their designs’ geometry for defects, as well as collaborate with customers and offsite members of the design crew in real time via the Internet before constructing a prototype.