You can find spinners on the Dart family of MIDI controllers, both optical and conductive (which is also DIY friendly)
That being said, the combination of all that stuff into one controller is pretty impressive. What I like most is the wheelboard, that looks like it can do so much more than knobs or faders.
Although I think that 8 or 16 wheels would be totally sufficient for my needs. Looking forward to the DIY options.
Does it allow for macros, or only one CC per wheel?
Because I think that different patches often benefit from different forms of expression, and just mapping raw synth parameters (even if there is relative control) can make expression harder than it needs to be. And many synths don’t allow for macro control, so putting all this together is really powerful, imagine having A4-like macros for all your synths, or even across devices.