I had an idea for a similar project. Basically, a tabletop drum kit. In this case, you’d tap on a few objects on the table that make distinct sounds and then map that back to a virtual drum kit in your DAW using midi. I never got around to building it, but I am still keen on the idea.
That already exists in some forms, most notably perhaps in Dubler 2.
I’m also working on an open source version of something similar, albeit quite involved and aiming at professional real-time performance and drumkit augmentation (if all goes well to share on HN this month for the first time :))