The intent of song personalization is good. But knobs and physical hand tools won’t result in breakthrough
I see two possible paths forward. The first is an app that can be loaded on any tablet which has permitted access to some form of the raw tracks from Pro Tools or Logic or whatever recording software is used by the artist. The app would then allow personalization on the condition that all personalized songs “mastered” by the user ( user can opt out) become property of the app maker, who then acts as third party distributor and royalty obligor to the artist. That incentivizes quality personalization and allows the artist to financially benefit from his or her fans’ efforts.
The other is a live version of the app tethered to a real digital drum machine operated by feet and hands. Imagine a drum quadrant where some lucky fan(s) gets to hit a digital snare, kick, tom, and hi hat etc with their feet while using free hands to punch another hand interface that generates other drum sounds. Maybe be the main audience can’t hear the fan generated percussion etc, but a room or separate area can be dedicated for such percussion and other fan track overrides. You would essentially be seeing two shows for the price of one. The really good customizations could then be selected by the artist for distribution.
That’s my vision. And it’s totally viable with good computer science and digital instrument design; much better than knobs or physical box — something that seems better suited for children as toys.