Therabands are excellent. I struggled with this a bit at the beginning, but once I bought a section of blue Theraband, I haven't had to fiddle with the plane. They just work great!
Tip: Don't make your theraband prop saver bands too thick. That makes it really hard to install, and can actually warp the props. Each application is a little different and you'll figure out how thick to make them for your own application. Sizing them about as wide as they are thick seems to work well as a start.