Dyne's 99-99 Build

[Vagabond Elf]

While returning from the con and browsing the Star Wars: Visions "The Ninth Jedi" episode guide I came across concept art for 99-99 by Tetsuya Nishio that I hadn't seen before.  

That concept art makes it look like the original plan was that Four-nines would move by rolling, using the centre ball as an impeller and the yellow-and-white arms as outriggers.  Which makes me suspect that having him float was an animation shortcut.

Now, if I were to attempt a rolling version I'd probably scale him up a bit, just to have some more room!

But that's not on-screen so not canon in any case.  And this build is very cool!  Eebel's build does a good job capturing the animation look, but it seems a bit bland in real life.  Yours looks more like a "real" droid, to my eye.