de ja vu!
there's another thread here in exactly the same link, posted same day... doo, doo ,doo, doo... doo, doo, doo, doo...
very innovative and elegant idea! I like it! I'd like to know how well it performs in practice...
Looks to me like the ball rests on three supports: 1 acts as a pivot point (or axle) and the other two drive the ball so it can track. So it looks to me like it has a lot of the simplicity of a push-to dobbie, the ability to track and you should be able to rotate the tube for convenience (of looking into the EP!)
Could be a challenge to mount a camera on? (and keep it balanced that is!)
Thanks for posting!
Al.