CodeSmith Generator ships with a sample project, CodeSmith.CustomProperties, that includes some useful property types for your templates:
- FileNameEditor can be used to let the user select a filename as the value for a property
- StringCollection can be used to let the user enter a collection of strings as the value for a property
You can find this project in your extracted samples folder (Documents\CodeSmith Generator\Samples\<VERSION>\Projects\CSharp\CustomPropertiesSample).