There’s a lot of these sort of chording synths out just recently, the NapkeyChord ( thread ) being extremely similar, but I think the Minichord sounds nicer, and is a nicer package, much more compact and holdable.
Another about to ship in a month or so is the HiChord ( post ), slightly different, and restricted to a key, but even more compact, plus they’ve added some interesting features to that.
The Minichord really needs to get taken up and manufactured if it is going to go anywhere.