I didn't implement a [knob], it's a two dimensional slider but the boundaries are a circle, anyway, still working on it.
I feel like implementing knob also and it'd be cool if I could implement a grid of knobs to control a routing matrix, but then I think it'd be way too heavy and impractical, so the best option would be to just have a way to draw circles in Data Structures with a dedicated object.
I see Purr Data has a [draw] object that draws circles and stuff, but it's a whole different GUI language that we can't use, but we could use one for vanilla.
It's out of my league, but I hope someone else could propose the inclusion of such object.
cheers