[DampRobot]

Originally Posted by Richard

Is your model parametric, so that you can drive dimensions for a wrench of any size from a table? Since this is a learning exercise, making the model parametric would be a good goal. Might even lead to useful results, or at least to interesting artistic combinations.
(Ooh, really bad pun.)

While changing a variety of parameters based on a table would be one way to do it, you could also create multiple configurations of the same part. I'm not as well versed in SolidWorks as I am in Inventor, but I believe this is the way that professionally modeled parts (like screws, etc.) are given multiple sizes.