How to prepare your model and set the options to use the Rail surface tool.
Prepare to use the Rail surface tool
Set up the options for the Rail surface tool
The Surfaces > Swept Surfaces > Rail Surface tool has options that control how many Generation Curves and Rail Curves it expects.
You can open the tool’s option box and change those options depending on how many curves you have whenever you use the tool.
Or, you can set up multiple custom versions of the tool on a shelf, corresponding to the different combinations of Generation Curves and Rail Curves options. See the section Create custom tools for more information.