I’ve seen a DIY version of something similar before https://www.instructables.com/Drawbot/ and I think there are older ones too.
The difference is including the motors in the hub instead of having them anchored, which is a cool idea, and the pen changer, which is a big upgrade.
I’d be curious how they cap what I assume are felt-tip markers to keep them from drying out. I have contemplated a few ideas for how to make a color-changing pen head for MPCNC. Some ball-point pens can be left uncapped, and the only other feasible thing I’ve encountered are retractable sharpies. I haven’t purchased any but it looks like they have some mechanism to seal the pen so it doesn’t dry out when retracted.
I was thinking of a stationary post, and the machine could physically click the markers against it to extend and retract them. And a carousel like @Madgrizzle had developed: Crazy Idea: Pen Color Change With E0?