videos
https://www.youtube.com/watch?v=th9v66KzUCI&feature=youtu.be
https://www.youtube.com/watch?v=nSWsuVO5O_Q
https://www.youtube.com/watch?v=hSZ8BhqtTVA
https://www.youtube.com/watch?v=BdZcVEC8SZU
various approaches
http://electro-music.com/forum/post-382662.html
https://mitxela.com/projects/ribbon_controller
http://electro-music.com/forum/viewtopic.php?t=61389
http://modularsynthesis.com/cvs/cvs3.htm