In MechDesigner you will find the 'Design Sets' tool. This tool allows you to compile a list of dimensions and parameters that are critical to a design 'variable' you want to optimize.  You can then edit the dimensions and parameters as part of a Design-Set.  The dimensions may be associated with different parts in one mechanism or even different parts in different mechanisms. This is a very efficient way of optimizing your design because the changes you make to a dimension or parameter are immediately reflected in the model, even while the mechanism or model is cycling. In this interactive way, you can 'look-and-see' in real-time. We believe this is the most practical way to give engineers a means to optimize their designs.