Learn more about this tool from Design Reform via Nate.
The free version (a paid subscription version due out soon will offer family form making) supports the following OpenNURBS geometry types:
- NURBS Curves (Drawn as approximated line segments)
Update 5/8/2016: CASE and the CASE Apps website are no more but, courtesy of WeWork, the CASE Apps are now open source. They may be accessed on GitHub.