From Fedora Project Wiki
There are tons of tutorials on how to create RPM packages, but many of them are obsolete, or don't include the important Fedora-specific stuff. This page gives the basics, with links to more information. I had to use many different sources to come up with this page - which was the problem in the first place.
The documentation for the -c option for the %setup macro doesn't seem to match how things work. -c just seems to trigger directory creation, but not choose the name. You still need to use -n name if you want a specific name.