Franklin Glider/Roller Capo
Put it on once. Just once. Leave it on and roll it up to where you would put your normal capo. If you need to change keys in the middle of a song, just roll the capo up or down as needed. Here's a video from Greg Bennett, creator of the Roller Capo:
https://www.youtube.com/watch?v=IYs3b0VP24U