I just learned that the two introductory images presented in the article on the Revit form creation API came from Zach Kron, whose blog Buildz presents lots of interesting 'practical notes on making impractical things' in Revit.
Here is a pointer to a completely different kind of practical note on another blog:
Several developers have been struggling with some of the hard-coded Revit behaviour. Miroslav Schonauer just pointed out that he and Sarah Capes found a solution for one specific problem on an Autodesk Consulting project, which is documented in this article on how to disable auto setback in a framing template.
And to round off today's potpourri, here is another issue around the topic of form creation:
Question: I am trying to use the NewSweptBlend method, but it throws an exception saying “The attempted operation is not permitted in this type of family.” What can I do to solve this?
Answer: This indicates that swept blends are not supported in the category type of the family where you are attempting to create it.
If it is a 2D family type, you would get this exception, and maybe also on a few other types as well.
In your specific case, the code uses a Conceptual Mass template and tries to create a SweptBlend in it. If you want to work in a Conceptual Mass template, you must use the NewSweptBlendForm method instead. If you want to use NewSweptBlend, then use a non-mass template. Note the difference between a generic model and conceptual mass.