[s_forbes]

It's usually much easier to buy gears than it is to manufacture your own. Some sites like McMaster Carr have CAD models of the parts they sell, so there is no need to create your own model.

If you need to create a gear in Solidworks that you can't find a model for, the Toolbox works very well. In an assembly you can insert a part that has the desired number of teeth and diametrical pitch, then edit it if necessary.